It's no secret that backing up your data is a good idea, and the same goes for your code. However, keeping a lot of slightly renamed versions of your files for every little modification is probably not the way to go.

Version Control Systems (VCS) allow not only to back up your files, but also, more importantly, help you to keep track of the different versions and what changed in each of them. Even better, multiple people can simultaneously work on one file and then easily combine the different changes.