Git

you can thank our lord savior linus torvald (founder of Linux) for making git available to everyone

It takes "saving your work" to a new level. It's a lot like the snapshots feature for virtual machines

Pro's:

• there are many source repo platforms that support git.
• it has many client programs like smart-git
• very easy to script
• there is many documentation
• a real must when your somewhat into programming or scripting
• great integration with many IDE's like VSCodium or IntelliJ
• it's has CLI and GUI

Con's:

• it can have a steep learning curve.

free and open source.

I find git needlessly complicated in comparison to Mercurial, so I use that instead.

Fast, a bit too intimidating at first without proper basics, but one of the better alternatives and by far the most popular choice

Great to see, that unlimited private repositories are now included in the free plan!