Best Version Control Software?

[beergood]

Can someone recommend a good version control software? I've been working on a rather large system and its getting to where I need something better than a notebook to track what I've changed. Anyone?

The system is PHP if that matters. I've never used version control before but I hear it helps.

[raymor]

What is best for you depends on a few factors, but most medium to large projects CVS.
Bitkeeper is also one to consider for some projects.
It's used for the Linux kernel even though it has a restrictive license.
Clearly Linus would have had to see some significant
advantages in Bitkeeper over open source tools like
CVS for him to force the kernel developers to use it.

This page gives and overview of many options:
http://www.linuxmafia.com/faq/Apps/scm.html

[dnsmonster]

I've been using SourceSafe, which comes with Vistual Studio. It's not all smooth but works for me.

[Linguist]

I'd recommend CVS... it's easy to learn and use... has its disadvantages but it's become almost the standard in software development