as our friends said it has the ability to safe running of 
the project, by useing this we can know the modifications 
made, and the persons who had done the modifications by 
selecting the "History"(Give the Right click on the file or 
project then select the History, u vil get the history of 
that). One more advantage with this is u can differentiate 
the present project r file with the older (Comarision of 
files or projects can be done)by simply selecting the two 
files or any thing which u want and then give the right 
click then click on the "Compare". We get the differences 
between the two. it has lot of uses. if possible i vil 
attach the material regaring VSS , but i need a couple of 
days,k.

Guys if i am wrong, pls correct me