Source control is an important part of development, whether it be for a website, a major application, or robot instructions/thoughts because you never know what you might have accidently made a chang that cauesed everything to go foobar on you.
Source control essentually allows to organize projects, and save files over and over again while saving the information on what was edited(much more but this is the simplified summary). This way you don't have to keep naming the file robotjumpthroughhoops001 ,002,003,etc . This doesn't happen automaticlaly though, so you will need to make sure that you do updates on a regular basis to your repository(location where file edits are saved to). Once you get used to this though, you may one day find out why this is such a great and useful tool to have in your robot buiding endevors, ie the foobar comment above.
There are several tools that you'll be able to use with the source control manager, one of the key ones is diff, which allows you to view the (wait for it...)differences in the two file versions plus any notes that you might have added. You did add notes to your updated version, right???
I recommand using subversion(svn for short). It can be run on the major os's(windows/linux/mac/etc) and has a large following, so finding info, help and tools shouldn't be an issue.
I also recommend playing around with the app first to get familiar with it .
here are some links that may also help in understanding and using version control tools
(the site above is pretty cool in general, and I recommend exploring it!)
As a side, this tool may not be for everyone, as it took me a while to get used to it, but since doing so, I've used it for qute a few other projects. This is a real world tool as well used in major industries(technology) and knowing how to use this tool could one day help to get a job somewhere!
Hope you all find this useful!!