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+---
+title: "Learning Git in Reverse"
+description: "A backwards introduction to the information manager from hell"
+tags:
+  - "Git"
+  - "Learning"
+  - "Talks"
+  - "zData"
+date: "2016-01-18"
+pubdate: "2016-01-20"
+categories:
+  - "Development"
+slug: "git-in-reverse"
+---
+
+> The content of this post is drafted from contents of a [similarly titled
+> presentation][23].
+
+It is certainly counter-intuitive to learn to drive by first going backwards,
+so why learn how to use Git in reverse? The short answer is: knowing the
+internals of Git _should_ make the commands and workflows of Git more
+accessible and understandable.
+
+We will start by touring the plumbing commands and walk all the way through
+branching.
+
+## What is Git± ##
+
+![XKCD on Git](http://imgs.xkcd.com/comics/git.png "If that doesn't fix it,
+git.txt contains the phone number of a friend of mine who understands git. Just
+wait through a few minutes of 'It's really pretty simple, just think of
+branches as...' and eventually you'll learn the commands that will fix
+everything.")
+
+Git is a few things to many people, and creating a standard definition is our
+first step to fully understanding the nebulous Git.
+
+Git, developed by Linus Torvalds, is a distributed version control system
+(DVCS). This means, Git is a tool for managing, typically, source code and its
+related versioning. It accomplishes this by creating a distributed acyclic
+graph of the code and folder structure and tracking the changes in the graph.
+
+Git internally accomplishes this by using a key-value or content addressable
+filesystem. Git only knows how to store "objects". There is really no other
+_real_ thing that Git is storing.
+
+## Plumbing ##
+
+We will start by learning a few of the most basic plumbing commands of Git,
+beginning with the [`git-hash-object(1)`][5] command:
+
+### Git Objects ###
+
+Git objects are a [zlib][3] compressed binary file stored under the
+`.git/objects` folder of any Git repository. They are typically created with
+the [`git-hash-object(1)`][5] command are very basic in content: several bytes
+of header information used by Git, type and size, and the full contents of the
+file Git is storing.
+
+For the majority of this post, we will be referencing objects created in a
+temporary repository:
+
+    $ cd /tmp
+    $ git init foo
+    $ cd foo
+
+> The [`git-init(1)`][4] command creates a new local Git repository in the
+> current directory or creates a new directory with a newly initialized Git
+> repository.
+
+After creating a new Git repository, let's examine its current contents:
+
+    ± find .git
+    .git
+    .git/objects
+    .git/objects/info
+    .git/objects/pack
+    .git/config
+    .git/HEAD
+    .git/hooks
+    .git/hooks/post-checkout
+    .git/hooks/post-commit
+    .git/hooks/ctags
+    .git/hooks/post-merge
+    .git/hooks/post-rewrite
+    .git/refs
+    .git/refs/tags
+    .git/refs/heads
+
+We see that Git has created several folders and files for its internal usage.
+We, as developers and users of Git, should generally never need to do anything
+to these files, with a small exception for `.git/hooks`.
+
+As noted before, `.git/objects` will be where Git will store all the objects
+(source code and related) we create. `.git/hooks` are used for add custom
+operations (white-space, conversions, `ctags`, etc.) to Git's operation.
+`.git/refs` is where Git stores information about tags and branches.
+`.git/config` is a file for local Git configuration options. This file will
+store information about our repository and where it will go for
+synchronization. `.git/HEAD` stores a reference to the working copy commit
+hash.
+
+With all this out of the way, we can now start creating objects.
+
+#### [`git-hash-object(1)`][5] ####
+
+We can start out by providing some content for [`git-hash-object(1)`][5]:
+
+    ± echo 'foo' | git hash-object --stdin
+    257cc5642cb1a054f08cc83f2d943e56fd3ebe99
+
+[`git-hash-object(1)`][5] typically expects filenames, so we provide `--stdin`
+to tell it we are passing contents from the standard input stream.
+
+However, since we haven't told Git to store the contents, we have no objects
+stored in the `.git/objects` folder. We will need to pass the `-w` flag to
+[`git-hash-object(1)`][5] to tell Git to store the contents.
+
+    ± echo 'foo' | git hash-object -w --stdin
+    257cc5642cb1a054f08cc83f2d943e56fd3ebe99
+
+Now, if we examine the `.git/objects` folder, we will see a new folder and a
+new file:
+
+    ± find .git/objects -type f
+    .git/objects/25/7cc5642cb1a054f08cc83f2d943e56fd3ebe99
+
+When Git stores objects, it splits the 40 character hash into two parts: the
+first two characters and the last 38. The first two characters, in this case
+25, as the folder, and the last 38, `7cc5642cb1a054f08cc83f2d943e56fd3ebe99`,
+as the file. The purpose of splitting the hash is to make indexing quicker.
+Some of the original motivations for developing Git was a requirement of speed
+and performance, can't manage decades of kernel history with a slow tool.
+
+We can use another Git plumbing command to extract the contents of the object:
+`git-cat-file`:
+
+    ± git cat-file -p 257cc5642cb1a054f08cc83f2d943e56fd3ebe99
+    foo
+
+Passing `-p` to `git-cat-file` tells Git to infer the type of the object.
+Otherwise, we need to tell Git what the object is.
+
+Moreover, because we know the objects are zlib compressed, we can use a tool
+like `zlib-flate` or similar to peer inside the contents of the files
+ourselves:
+
+    ± cat .git/objects/25/7cc5642cb1a054f08cc83f2d943e56fd3ebe99 \
+    >   | zlib-flate -uncompress
+    blob 4foo
+
+Here we see the metadata that Git uses itself, but is otherwise the contents we
+expect.
+
+Perfect. We can store content in Git's object store and we can retrieve the
+contents. However, attempting to manage files in this way will be more taxing
+than any form of development. Furthermore, we don't have a way to store
+filenames yet. Thus, we will need a new type of object, trees.
+
+### Git Trees ###
+
+Trees are objects.
+
+Trees are similarly zlib compressed binaries of the internal data structure of
+tracked folder structure of the repository. We create Git trees using the
+[`git-update-index(1)`][6] and [`git-write-tree(1)`][7] plumbing commands.
+
+Since we have an object already added to the Git object store, we can go ahead
+and create a basic tree:
+
+    ± git update-index --add --cacheinfo 100644 \
+        257cc5642cb1a054f08cc83f2d943e56fd3ebe99 foo.txt
+    ± git write-tree
+    fcf0be4d7e45f0ef9592682ad68e42270b0366b4
+
+Thus far, we have created two objects, one to store the contents of `foo.txt`
+and another as the tree, which stores binding between the contents and the
+filename for `foo.txt`.
+
+Visually, this may look like something similar to the following image:
+
+![Git Tree 1][git-tree-1]
+
+If we inspect the `.git/objects` directory, we should see a new object:
+
+    ± find .git/objects -type f
+    .git/objects/fc/f0be4d7e45f0ef9592682ad68e42270b0366b4
+    .git/objects/25/7cc5642cb1a054f08cc83f2d943e56fd3ebe99
+
+As we expected, there is a new folder and new file, `fc` and
+`f0be4d7e45f0ef9592682ad68e42270b0366b4`, respectively.
+
+Since Git trees are actually objects, we can use the `git-cat-file` command
+again to print out the contents of the tree:
+
+    ± git cat-file -p fcf0be4d7e45f0ef9592682ad68e42270b0366b4
+    100644 blob 257cc5642cb1a054f08cc83f2d943e56fd3ebe99	foo.txt
+
+That is, trees are objects where the contents of the object describes a folder
+structure "tree". It uses 4 columns for each element of the tree where the
+first number uses something similar to the Unix permissions octals; the second
+defines the type of object, this can be either `blob` or `tree`; the third is
+the hash of the object the entry points to; finally, the last element is the
+filename of the object or folder name if the element is a tree.
+
+A more complicated example of a Git tree may look like the following image:
+
+![Git Tree 2][git-tree-2]
+
+Now we have file names and the ability to track folders, however, we are still
+managing and holding onto the checksums ourselves. Furthermore, we have no
+reference to who, when, why, or from where changes are being made. We need
+another object to store this information.
+
+### Git Commits ###
+
+This will sound familiar: Git commits are ... objects.
+
+Git stores commits the same way it stores files and trees, as a zlib compressed
+binary in the `.git/objects` folders. Similar to trees, the contents of the
+object is specifically formatted, but they are stored the same nonetheless. We
+can create commits using the [`git-commit-tree(1)`][8] plumbing command.
+
+The [`git-commit-tree(1)`][8] command takes a message, a tree, and optionally a
+parent commit, and creates a commit object. If the parent is not specified, it
+creates a root commit.
+
+We have just created a tree, let's see what committing that tree looks like:
+
+    ± echo 'our first commit' \
+    > | git commit-tree fcf0be4d7e45f0ef9592682ad68e42270b0366b4
+    d7ee3cdd8bfcc1b8c3f935302f2d2e78e69e4197
+
+> Notice, the hash returned here _will_ be different. This hash is dependent on
+> time and the author.
+
+Inspecting our `.git/objects` store, we will see our new object:
+
+    ± find .git/objects -type f
+    .git/objects/d7/ee3cdd8bfcc1b8c3f935302f2d2e78e69e4197
+    .git/objects/fc/f0be4d7e45f0ef9592682ad68e42270b0366b4
+    .git/objects/25/7cc5642cb1a054f08cc83f2d943e56fd3ebe99
+
+Similar to trees and files, we can use the `git-cat-file` command to inspect
+the newly created commit object:
+
+    ± git cat-file -f d7ee3cdd8bfcc1b8c3f935302f2d2e78e69e4197
+    tree fcf0be4d7e45f0ef9592682ad68e42270b0366b4
+    author kballou <kballou@devnulllabs.io> 1453219069 -0700
+    committer kballou <kballou@devnulllabs.io> 1453219069 -0700
+
+    our first commit
+
+Breaking down this structure, we have 4 lines, the first line tells which tree
+this commit is saving. Since a tree already contains the information of all the
+objects that are currently being tracked, the commit only needs to save the
+root tree to be able to save _all_ the information for a commit. The second and
+third line tell us the author and committer, often these will be the same. They
+will be different for GitHub pull requests, or in other situations where the
+author of the patch or change is different from the maintainer of the project.
+Finally, after a blank line, the rest of the file is reserved for the commit
+message; since "our first commit" message is short, it only takes a single
+line.
+
+![git commit 1][git-commit-1]
+
+To inform Git that we have created a commit, we need to add some information to
+a few files. First, we need create the `master` reference. We do this by
+putting the full commit hash into a file called `.git/refs/heads/master`:
+
+    ± echo d7ee3cdd8bfcc1b8c3f935302f2d2e78e69e4197 > .git/refs/heads/master
+
+The next thing we should do is update the `.git/HEAD` file to point to our new
+reference:
+
+    ± echo 'ref: refs/heads/master' > .git/HEAD
+
+This brings Git up to speed on everything we have done manually, similarly,
+this is what Git does for us when we use the porcelain commands for managing
+code. However, it's not really recommended to be manually touching these files,
+and in fact, there is another plumbing command for updating these files:
+[`git-update-ref(1)`][9]. Instead of the two commands above, we can use a
+single invocation of [`git-update-ref(1)`][9] to perform the above:
+
+    ± git update-ref refs/heads/master d7ee3cdd8bfcc1b8c3f935302f2d2e78e69e4197
+
+Notice, [`git-update-ref(1)`][9] is an idempotent operation, that is, if the
+reference has already been changed to the current hash, running this command
+again will yield no change.
+
+Before we get into the porcelain commands, let's walk through the motions
+again:
+
+    ± echo 'bar' > bar.txt
+    ± git hash-object -w bar.txt
+    5716ca5987cbf97d6bb54920bea6adde242d87e6
+    ± git update-index --add --cacheinfo 100644 \
+    >   5716ca5987cbf97d6bb54920bea6adde242d87e6 bar.txt
+    ± git write-tree
+    b98c9a9f9501ddcfcbe02a9de52964ed7dd76d5a
+
+So far, we have added a new file, `bar.txt` with the contents of `bar`. We have
+added the file to a new tree and we have written the tree to the object store.
+Before we commit the new tree, let's perform a quick inspection of the tree:
+
+    ± git cat-file -p b98c9a9f9501ddcfcbe02a9de52964ed7dd76d5a
+    100644 blob 5716ca5987cbf97d6bb54920bea6adde242d87e6	bar.txt
+    100644 blob 257cc5642cb1a054f08cc83f2d943e56fd3ebe99	foo.txt
+
+An entry for `foo.txt` is present in this new tree. Git is implicitly tracking
+previous objects, and carrying them forward, we didn't have to do anything for
+Git to do this. Furthermore, the only new objects in the object store so far is
+the new object for the contents of `bar.txt` and the object for the new tree:
+
+    ± find .git/objects -type f
+    .git/objects/b9/8c9a9f9501ddcfcbe02a9de52964ed7dd76d5a
+    .git/objects/57/16ca5987cbf97d6bb54920bea6adde242d87e6
+    .git/objects/d7/ee3cdd8bfcc1b8c3f935302f2d2e78e69e4197
+    .git/objects/fc/f0be4d7e45f0ef9592682ad68e42270b0366b4
+    .git/objects/25/7cc5642cb1a054f08cc83f2d943e56fd3ebe99
+
+Now, we can commit this new tree using the [`git-commit-tree(1)`][8] command:
+
+    ± echo 'our second commit' | git commit-tree \
+    >   -p d7ee3cdd8bfcc1b8c3f935302f2d2e78e69e4197 \
+    >   b98c9a9f9501ddcfcbe02a9de52964ed7dd76d5a
+    b7fd7d75c1375858d8f355735a56228b3eb5e813
+
+Let's inspect this newly minted commit:
+
+    ± git cat-file -p b7fd7d75c1375858d8f355735a56228b3eb5e813
+    tree b98c9a9f9501ddcfcbe02a9de52964ed7dd76d5a
+    parent d7ee3cdd8bfcc1b8c3f935302f2d2e78e69e4197
+    author kballou <kballou@devnulllabs.io> 1453229013 -0700
+    committer kballou <kballou@devnulllabs.io> 1453229013 -0700
+
+    our second commit
+
+This commit should look very similar to the previous commit we created.
+However, here we have a line dedicated to the "parent" commit, which should
+line up with the commit passed to the `-p` flag of [`git-commit-tree(1)`][8].
+
+We can update the `master` reference, too, with the new hash:
+
+    ± git update-ref refs/heads/master b7fd7d75c1375858d8f355735a56228b3eb5e813
+
+Let's modify `foo.txt` and create another commit:
+
+    ± echo 'foo 2' > foo.txt
+    ± git hash-object -w foo.txt
+    a3f555b643cbba18c0e69c82d8820c7487cebe15
+    ± git update-index -add --cacheinfo 100644 \
+    a3f555b643cbba18c0e69c82d8820c7487cebe15 foo.txt
+    ± git write-tree
+    68b757546e08c1d9033c8802e4de1c0d591d90c8
+    ± echo 'our third commit' | git commit-tree \
+    >   -p b7fd7d75c1375858d8f355735a56228b3eb5e813 \
+    >   68b757546e08c1d9033c8802e4de1c0d591d90c8
+    354c7435a9959e662cea02495957daa93d875899
+    ± echo 354c7435a9959e662cea02495957daa93d875899 > .git/refs/heads/master
+
+This final example, we have gone from creating a file, adding the file to a
+tree, writing the tree, committing the tree, and finally, pushing forward the
+`master` reference.
+
+There are a few more points to make before we go onto a brief tour of the
+porcelain commands.
+
+Let's go ahead and inspect the current state of the object store:
+
+    ± find .git/objects -type f
+    .git/objects/35/4c7435a9959e662cea02495957daa93d875899
+    .git/objects/68/b757546e08c1d9033c8802e4de1c0d591d90c8
+    .git/objects/a3/f555b643cbba18c0e69c82d8820c7487cebe15
+    .git/objects/b7/fd7d75c1375858d8f355735a56228b3eb5e813
+    .git/objects/57/16ca5987cbf97d6bb54920bea6adde242d87e6
+    .git/objects/b9/8c9a9f9501ddcfcbe02a9de52964ed7dd76d5a
+    .git/objects/d7/ee3cdd8bfcc1b8c3f935302f2d2e78e69e4197
+    .git/objects/fc/f0be4d7e45f0ef9592682ad68e42270b0366b4
+    .git/objects/25/7cc5642cb1a054f08cc83f2d943e56fd3ebe99
+
+There's a few things to notice here, every object we have created so far is
+_still_ in the object store, the first version of `foo.txt` is still there
+(`257cc5642...`). All the trees are still there, and of course the commits are
+still around. This is because Git stores objects. It does not store computed
+differences or anything of the sort, it simply stores the objects. Other
+version control systems may store the patches, individually version files,
+or even track file renames. Git does none of this. Git simply stores only the
+objects you ask, it doesn't store the differences between any files, it doesn't
+track that a file was renamed. Every commit points to the exact version of
+_every_ file at that point in time. If a difference between the working file
+and the stored version is asked for, it's computed, if a difference between
+yesterday's version of a file and today's, it's computed. If a file was
+renamed, it can be inferred by a similarity index and computing the difference
+between Git trees. This achieves tremendous performance gains because computing
+text differences is relatively cheap compared to attempting to manage code
+patches as a means of versioning.
+
+## Porcelain ##
+
+Now that we have gone through our tour of the plumbing commands and Git
+internals, we can start _actually_ use Git. It will be very rare that the
+typical user of Git will ever be using any of the plumbing commands above or
+touching files under the `.git` folder in their day-to-day work. For the
+day-to-day usage of Git, we will be using the "porcelain" commands, the
+commands that take the arduous steps above, and turn them into a pleasant walk
+in the park. Essentially, everything we have done above can be accomplished
+with two (2) commands in Git: [`git-add(1)`][10] and [`git-commit(1)`][11].
+
+Let's initialize a new temporary repository for demonstration:
+
+    $ cd /tmp
+    $ git init bar
+    $ cd bar
+
+After initializing the repository, we can add a file, say, `foo.txt`:
+
+    ± echo 'foo' > foo.txt
+
+Next, we can use the [`git-add(1)`][10] command to stage the file to be
+tracked:
+
+    ± git add foo.txt
+
+Next, we can use the [`git-commit(1)`][11] command to commit the newly created
+`foo.txt` file:
+
+    ± git commit -m 'initial commit'
+
+Everything we have done so far is now achieved with these two commands. We have
+stored the contents of the file, created a tree, and committed the tree.
+
+There are a few more commands that are very useful to using Git on a regular
+basis: [`git-clone(1)`][12], [`git-status(1)`][13], [`git-log(1)`][14],
+[`git-pull(1)`][15], [`git-push(1)`][16], and [`git-remote(1)`][17].
+
+### [`git-clone(1)`][12] ###
+
+Before you can contribute to a project, you need your own copy of the
+repository, this is where we would use [`git-clone(1)`][12]. As we have seen
+before, we can create _new_ repositories with [`git-init(1)`][4], but we still
+need a means of getting existing work from another source.
+
+Here's an example of using `git-clone`:
+
+    $ git clone git://github.com/git/git.git
+    ...
+
+There are several protocols that can be used for the when cloning, listed here
+in order of preference:
+
+*   `SSH`
+
+    -   Bi-directional data transfer
+
+    -   Encrypted
+
+    -   Typically authenticated, especially without passwords
+
+*   `Git`
+
+    -   Pull only
+
+    -   Intelligent transfer mechanism
+
+*   `HTTP/S`
+
+    -   Bi-directional data transfer
+
+    -   Authenticated
+
+    -   Unintelligent transfer mechanism
+
+*   `File`
+
+### [`git-status(1)`][13] ###
+
+Often, you will need to know the state of the current repository, and the go-to
+command to view the current state of the repository is the
+[`git-status(1)`][13] command. It will give you information about the currently
+modified files, the currently untracked files, the branch you're one, if the
+branch is tracked upstream, it will let you know if you have something to push,
+etc.
+
+### [`git-log(1)`][14] ###
+
+[`git-log(1)`][14] is used to check the history of the repository. Using
+[`git-log(1)`][14] with a few arguments, you can get a pretty concise image of
+how your projects are changing.
+
+Some commonly used options you might use might be:
+
+*   `--stat`: Show the files and number of changes for each commit
+
+*   `--oneline`: Show each commit on a single line
+
+*   `--summary`: Show condensed summary of header information
+
+### [`git-pull(1)`][15] and [`git-fetch(1)`][18] ###
+
+[`git-pull(1)`][15] is used to pull remote changes into your current working
+copy. I prefer not use [`git-pull(1)`][15] because I find it to be slightly
+[harmful][19].  Instead, I use either [`git-fetch(1)`][18] or a form of
+[`git-remote(1)`][17].
+
+[`git-fetch(1)`][18] is a similar command used for "fetching" remote changes,
+but does not attempt to automatically merge them into the local branch.
+
+### [`git-push(1)`][16] ###
+
+[`git-push(1)`][16] will send your changes to the remote location. By default,
+this command will not attempt to overwrite the remote if the changes cannot be
+applied with a "fast-forward" merge operation.
+
+### [`git-remote(1)`][17] ###
+
+[`git-remote(1)`][17] is an overall "remote" management command. It allows you
+to add remotes, rename remotes, and even fetch information about remotes.
+"Remotes" are non-local/upstream sources of changes. The remote "origin" is the
+default name for the remote of a clone. This could be a co-worker's repository
+or it could be the central repository of the project.
+
+With the [`git-remote(1)`][17] command, we can add a new remote:
+
+    ± git remote add upstream proto://remote
+
+We can rename a remote:
+
+    ± git remote rename origin upstream
+
+And my favorite, we can fetch changes from the remote:
+
+    ± git remote update -p origin
+
+I use this last command so much, in fact, I have created an alias in my
+`~/.gitconfig` file:
+
+    [alias]
+        up = !git remote update -p
+
+This way, I can decide when and _how_ I want to merge the upstream work into my
+local copy.
+
+The above commands along with `git-add` and `git-commit` will cover the
+majority of Git related tasks, as far as simple, non-branching workflows are
+concerned.
+
+For more advanced usage of Git, we can continue to learn about code branching,
+git branches, and merging techniques.
+
+## Branches ##
+
+Git branches are actually a very simplistic concept in both implementation and
+intuition. Code and applications versioned by any version control tool have
+their implicit branching points: when one user commits code that another user
+isn't yet made aware, the code has diverged from a single path of existence to
+multiple paths. This is a form of implicit branching and explicit branching
+isn't much different.
+
+![Code Branching][code-branching]
+
+The structure of Git makes branching trivial, in fact, all that's required is
+to create a file that marks the branch point of the code. That is, to create a
+file under `.git/refs/heads` that contains the branch's base commit hash. From
+there, the code can safely move forward without changing anything of the other
+branches.
+
+![Git Branching][git-branching-1]
+
+Branching in Git is accomplished with [`git-branch(1)`][20] and
+[`git-checkout(1)`][21].
+
+The basic form of [`git-branch(1)`][20] is the following:
+
+    ± git branch {branch_name} [optional branch point]
+
+If the branch point is not specified, [`git-branch(1)`][20] defaults to the
+`HEAD` reference.
+
+Once the branch is created, you can switch to it using the
+[`git-checkout(1)`][21] command:
+
+    ± git checkout {branch_name}
+
+Moreover, if you're going to be creating a branch and immediately switching to
+it, you can use the `-b` flag of [`git-checkout(1)`][21] to do these two steps
+in one:
+
+    ± git checkout -b {branch_name} [optional branch point]
+
+## Merging ##
+
+Once you're ready to merge your changes from one branch into another branch,
+you can use the [`git-merge(1)`][22] command to accomplish that.
+
+There are a few different ways Git can merge your work between two branches.
+The first Git will try is called "fast-forward" merging, where Git will attempt
+to play the source branch's commits against the target branch, from the common
+history point forward.
+
+![Git Fast Forward Merge Initial][git-ff-merge-1]
+
+![Git Fast Forward Merge Replay][git-ff-merge-2]
+
+However, this can only be accomplished if the target branch doesn't have any
+changes of its own.
+
+If the target branch _does_ have changes that are not in the source branch,
+Git will attempt to merge the trees and will create a merge commit (assuming
+all went well). If a merge conflict arises, the user will need to correct it,
+and attempt to re-apply the merge, the resolution of the merge will be in the
+merge commit. For more information on merging, see the [`git-merge(1)`][22]
+documentation.
+
+![Git Resolve Merge][git-resolve-merge]
+
+## Summary ##
+
+Git is not the most complicated version control system out there, and I hope
+peering into the internals of Git demonstrates that fact. If anything, it may
+seem that Git is very simplistic and unintelligent. But this is actually what
+gives Git its power. It's simplistic (recursive) object storage is what gives
+Git super powers. Git can infer file renames, branching is trivial, merging is
+similarly easier, the storage and tree model are well understood concepts and
+the tree and graph algorithms are well studied.
+
+However, this simplistic approach to storage also has a few problems. Tracking
+binary files tends to be expensive because Git isn't storing the difference,
+but each version of the file in its entirety. The zlib compression library also
+isn't always amazing at compressing binary files either.
+
+Beyond these problems, Git is a very powerful and capable source control tool.
+
+### References ###
+
+[1]: http://git-scm.com/
+
+*   [Git SCM Site][1]
+
+[2]: http://git-scm.com/book/en/v2
+
+*   [Apress: Pro Git][2]
+
+[3]: https://en.wikipedia.org/wiki/Zlib
+
+*   [zlib compression][3]
+
+[4]: https://www.kernel.org/pub/software/scm/git/docs/git-init.html
+
+[5]: https://www.kernel.org/pub/software/scm/git/docs/git-hash-object.html
+
+[6]: https://www.kernel.org/pub/software/scm/git/docs/git-update-index.html
+
+[7]: https://www.kernel.org/pub/software/scm/git/docs/git-write-tree.html
+
+[8]: https://www.kernel.org/pub/software/scm/git/docs/git-commit-tree.html
+
+[9]: https://www.kernel.org/pub/software/scm/git/docs/git-update-ref.html
+
+[10]: https://www.kernel.org/pub/software/scm/git/docs/git-add.html
+
+[11]: https://www.kernel.org/pub/software/scm/git/docs/git-commit.html
+
+[12]: https://www.kernel.org/pub/software/scm/git/docs/git-clone.html
+
+[13]: https://www.kernel.org/pub/software/scm/git/docs/git-status.html
+
+[14]: https://www.kernel.org/pub/software/scm/git/docs/git-log.html
+
+[15]: https://www.kernel.org/pub/software/scm/git/docs/git-pull.html
+
+[16]: https://www.kernel.org/pub/software/scm/git/docs/git-push.html
+
+[17]: https://www.kernel.org/pub/software/scm/git/docs/git-remote.html
+
+[18]: https://www.kernel.org/pub/software/scm/git/docs/git-fetch.html
+
+[19]: http://stackoverflow.com/questions/15316601/in-what-cases-could-git-pull-be-harmful#15316602
+
+*   [SO: Cases `git-pull` could be considered harmful][19]
+
+[20]: https://www.kernel.org/pub/software/scm/git/docs/git-branch.html
+
+[21]: https://www.kernel.org/pub/software/scm/git/docs/git-checkout.html
+
+[22]: https://www.kernel.org/pub/software/scm/git/docs/git-merge.html
+
+[23]: https://kennyballou.com/git-in-reverse.pdf
+
+[code-branching]: https://kennyballou.com/media/code-branching.png
+
+[git-branching-1]: https://kennyballou.com/media/git-branching-1.png
+
+[git-commit-1]: https://kennyballou.com/media/git-commit-1.png
+
+[git-ff-merge-1]: https://kennyballou.com/media/git-ff-merge-1.png
+
+[git-ff-merge-2]: https://kennyballou.com/media/git-ff-merge-2.png
+
+[git-resolve-merge]: https://kennyballou.com/media/git-resolve-merge.png
+
+[git-tree-1]: https://kennyballou.com/media/git-tree-1.png
+
+[git-tree-2]: https://kennyballou.com/media/git-tree-2.png
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