Howdy:
A simple search at microsoft could have saved you the time of coming here, asking the question and waiting for a reply..
As per Microsoft...
Windows XP creates “restore points” every day, as well as at the time of significant system events (such as when an application or driver is installed). You can also create and name your own restore points at any time.
More... This feature works like the Undo command in a word processing program. System Restore automatically monitors and records key system changes. If you change a system setting and then discover a problem, you can easily reverse the change.
Murray