I can't believe how many web developers don't use a source control system when a product like this is available for free. I've been so successful using this for html & script files.
You never need to rename your old versions to .bak, .bak.old, or whatever when you put your files under rcs control. The 10 minute tutorial really teaches you what you need to be productive right away. It's easy to see your latest source code changes and compare previous version. The window interface for this product makes it easy for me me to do 95% of what I need, and I've been very happy using the command line interface. This is great for maintenance/support of applications. It promotes application stability and programmer sanity!
Note: This review is for the freeware single user release, not the multiplatform/multiuser version.
