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Now, in the last lesson, we spoke about some of the more basic variants of version control.
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Now, in this lesson, I want to talk about branches and branching.
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Now, let's start off with a simple example, say, if we had version 1 and 2,
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so two commits that were made to our local repository.
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Now, at this point, we realize that we want to maybe try out something different, maybe build a new feature,
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or just to mess around with a new idea or concept.
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So what we can do is, instead of continuing to commit to the master branch, which is the main branch that
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you see here, we can also create a side branch so we can create as many branches as we like.
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So after the second commit, we create a new branch and we start committing to this new branch or this
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experimental branch. We add some features and we write some code.
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Now, simultaneously, we can continue working on the main branch, putting out all those essential updates
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or bits of code that are maintaining our main project. But at the same time, we can continue to update
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and work on this experimental branch trying things out and committing our experiment to this experimental
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branch.
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So, now we have two branches that are parallel to each other and they can be developed simultaneously.
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Now, if at some point in the future that we decide that that experiment was really fruitful and the feature
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that we built in it was really, really great and we'd like to merge it back to the main branch or to
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the main project, then that can be done really easily as well by simply placing a merge request in.
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And we can bring all of those changes that we experimented with, that we messed around with, back to the
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main project and check to see if there's any conflicts with the main branch code,
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and if not, or if after a little bit editing, then we can bring all of those changes into the main working
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master branch. And then we can continue working from here onto the next commit or we can make more branches.
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And very often what you see in practice is that there'll be multiple branches being worked on at the
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same time for any given large project.
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And the reason is because sometimes you're developing new features, sometimes you are fixing bugs,
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and all of these things may break your main project, so you don't want to do it on the master branch.
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You only want to put it on the master branch once you've tested, once you know that everything is working
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fine, and then you can bring your code back to the working copy ready for shipment and deployment.
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So let's take a look at how this would work in reality.
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Now, let's say, we navigate back to our Story directory.
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And inside here, we've still got our previous three chapters and they are under version control.
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So if we just have to look at git log, you can see that this is currently the most recent commit and it's
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also mirrored in our remotes.
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So let's try and do this locally first.
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If I decided I want to create a new branch, you can simply just write and get branch and specify the
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name of your new branch.
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So I'm going to add a space related plot to my story.
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So let's call our branch alien-plot.
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Hit enter. And now you can check out what branches you have by just writing git branch without the name
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and you can see that you've got one brand called alien-plot and another one called master, and the asterisk
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shows you which branch you are currently on.
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So we're currently on the master branch.
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We can switch to the alien-plot by simply writing "git checkout alien-plot."
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Okay.
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So as it says, we have now switched to the branch called alien-plot.
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Now, it is inside this branch that I'm going to make some changes to my chapters. So let's try doing that.
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Now, I'm going to make some completely nonsensical hum modification to my files.
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So let's change
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chapter1. Let's change chapter2.
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Okay. There we go. Okay.
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So we've made some modifications,
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chapter1, chapter2, and we've decided to change some of the preexisting written text to integrate a
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space themed or alien themed plot.
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So let's go ahead and commit that.
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So remember, we have to do git add, and then git commit -m.
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And our message is going to be "modify chapter 1 and 2 to have alien theme."
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Okay, now hit enter and we've made our commits.
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So, now if we do a git log, we can see that we have two commits made on the master branch and we have
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one commit made on the alien-plot branch.
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So, now let's say that we go back onto our master brunch.
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So whenever you're confused where you are, you can always do a git branch to check and see where the
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asterisk is, and the asterisk is, obviously, where you are.
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So let's do a git checkout master to go back to the master branch. So you can see that our master branch
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is unchanged with respect to the space or alien-plot that we did just now.
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Nothing has changed over here.
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So while on the master branch, I'm going to create a new file.
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I'm going to call that chapter4.txt. And inside chapter4,
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let's let's add something.
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Okay, and hit enter and say-- By the way, I have no idea what I'm typing.
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I'm now making up and destroying probably in the process a masterpiece.
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But it's okay.
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So we now have a chapter4 on our master branch and I'm going to go ahead and do a git add and
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git commit.
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Now, there's ways of combining add and commit together in the same command.
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But I think if you're new to git,
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it's always good to really know in your head exactly what's going on.
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So I recommend actually separating those two gits out.
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So let's go ahead and give it a commit message "add chapter 4."
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Okay, so git log.
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Let's see what have we got.
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So we are currently only looking at the master branch and we have three commits.
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This is the position of our remote.
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So on our GitHub repository, this was the latest commit that it could see.
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But on a local Git repository, this is in fact the latest commit, the one that we just made where we added
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chapter 4.
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And you can see that if I switch between the branches, say, if I go over to alien-plot branch and hit
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enter, you can see there are local files actually changed as I switched branches.
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So let's just say that I'm quite happy with the changes I've made in terms of my alien-plot addition,
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and I would like to merge these changes back into my master branch.
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So I've done a little bit of experimentation on a separate branch.
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I've messed with a few things.
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And I think it was a great experiment.
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So I'm going to put it back into our main master branch.
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So in order to do that, what you have to do is go back to the master branch, so "git checkout master."
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And while we're on the master branch, we're going to merge the changes inside the alien-plot branch.
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So we use the command git merge and we're going to specify the branch name which was alien-plot.
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Hit enter.
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And this opens up vim which is a text editor and this allows you to add a merge message if you wish.
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And alternatively, as we're going to do here which is going to leave it empty, and you're going to write 
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":q!" to save and quit. And you can see now I've actually absorbed those changes from the
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alien-plot.
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So I'm on my master branch. And you can see that because if I do git branch, I am on the master branch.
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So the alien-plot still exists by the way.
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So on the master branch, if you have a look at git log, you can see that I've got some of the previous
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commits. But I've also got this merge branch alien-plot which was my most recent commit.
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So, now at this point, let's do a git push to our origin master and remember to add the -u flag.
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So that's completed,
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and let's check it out online.
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So if we go over to our Story repository, you can see that there's now five commits.
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So we modify chapter 1 and 2, we added up to 4, and we merged the alien-plot branch.
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So if you're going to Insights, Graphs, and go to Network,
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now if I zoom in on this network graph and get rid of the tag, then you can see this is the process that
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we've gone through.
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So this is the master branch where we did chapter 1 and chapter 2.
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And then at this point, after I created chapter 2 and 3, I created a new branch. And while inside this
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branch, I made a commit that modified chapter 1 and 2 to have an alien theme.
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And then on the master branch, I continued developing the master branch adding a chapter 4.
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But subsequently, I realized that I did a great job of adding alien themes to our storyline and I decided
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to merge it back into the main branch.
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So this is basically a graphical representation of what's been going on. Now you can do everything I
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just did inside GitHub itself. And it's actually really easy to do.
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So let's go ahead and create a brand-new repository and I'm going to call this one Story2 because
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that's how imaginative I am, clearly not suited for story writing.
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Now, it's really important.
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We're going to leave our repository as public, but you're going to check this box to initialize your repository
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with a README.
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Now, README is simply a text file that tells other people what your GitHub repository is all about.
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So if you gone to any repository, let's just, I don't know, search for something like--
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And we go over here.
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You can see that this part that comes below the list of files is the README. And some people format
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this really heavily so that you can show various flags. But you can also tell people how to use your
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library, how to incorporate it into their project,
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basically, a whole bunch of useful stuff,
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anybody who is looking at your repository.
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So, now we've got our new repository. So you can click on the README file and you can make some edits
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if you wish.
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But what we're going to do is we're going to go into our main story to repository, and I'm just going
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to create a new file.
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So this is going to be, again, chapter1.txt. And in my new file, I'm just going to say, 
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"This is a story."
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I think I'm pretty much given up on writing stories now and we're going to make a commit.
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So this is going to be
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"Create chapter 1" and we're going to commit directly to the master branch.
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So commit new file.
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Okay, so now that we've got chapter1 and we are on the branch master, at this point, I'm going to create
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a new branch, and let's call this new branch experimental.
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Okay, so now we have experimental and it takes you straight to the experimental branch, copying over everything
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that you had at that point inside the master branch.
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And now inside this experimental branch, I'm going to make an edit to my chapter1.
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So I'm going to click on the file, not over here, but over here. And I'm going to click on the pencil button
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to edit this file.
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"This is a story." "This--" Nothing like a bit of confidence in your story writing to make it better,
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right?
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Okay, so now let's commit these changes and let's say, "Update chapter 1 to be more upbeat."
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Okay. Now, we're going to commit and we're committing.
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So always check to see where you're committing to because sometimes when you have a lot of branches
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and you're switching branches, then it can get quite confusing.
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So we're committing to the experimental branch and we're going to go ahead and commit those changes.
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Now, let's switch back to our master branch. And you can see immediately, this is reflected, so that new
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line that we had previously is now gone.
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So let's go back to our main repository file.
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You can see that you've already got this little notification here which is telling you that you've got
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a experimental branch and you can compare between your master and experimental and make a pull request.
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So we're going to talk about pull requests in more detail later on.
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But, basically, this is telling you, "Hey, you've got changes that are not reflected in your master branch.
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Do you want to pull those changes over to your master branch?"
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So right now, that's not we're going to do
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but instead, on our master brunch,
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So check to make sure that master is checked.
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We're going to create a new file and we're going to call it chapter2.txt and we're going to
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say, "This is an even better chapter." 
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Okay. So let's say, "Create chapter 2"  and we're committing to the master branch. So commit that file, and then
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we're going to check out what the structure of our repository looks like now, inside Graphs and inside
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Network.
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So you can see that we've got a initial commit, and then we have our created chapter1. And then after chapter1,
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we decide to make a brunch that was experimental, and then we continued where we left off in the master
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branch.
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So, now what I want to do is I want to go into that master branch and I want to merge those changes in
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the experimental branch over.
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So I want to pull those changes from the experimental branch to the master branch.
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So in order to pull, you have to be in the place that you're going to do the pulling which is the master
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branch.
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And while we're here, I'm going to say "New pull request," and this takes me to the Compare page.
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So here I can say that my base is my master branch and I want to compare it with my experimental branch.
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So we can see that the difference is only this line, so plus this line. When it's red, it's an erasure.
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When it's a plus,
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it's an addition.
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So whereas inside my master branch, this is all I've got inside chapter1. In my experimental branch,
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I've got all of this.
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So I have to say that I prefer this version in the experimental branch.
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So I'm very happy with what I did in the experiment.
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So I'm going to create a pull request that is going to merge these two branches.
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So, now once I've done that, I'm going to merge those two branches.
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So I'm going to say, "Merge experimental branch to master." And go ahead and confirm the merge.
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Now, you can see it's almost more straightforward doing it on the Terminal, but you get used to the interface,
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and this is not so complex either.
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So, now if we have a look at our Network graph,
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you can see that that experimental branch was pulled back to the master branch and merged.
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So that was us creating a branch and merging it.
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Now, why don't you go ahead and have a go and create your own repository, both locally and as well as
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on GitHub
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and, you know, write a story or write a poem, anything you like, and check out the amazingness that is
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branching using Git.