What is svchost.exe and what does it do?

[SCHUMIinSA]

I have often wondered about this. I usually have 3 or 4 in my processes and they tend to grow rather large. I presume they are Windows processes, but I wonder what they actually do and why they get so big.
What would happen if I just descided to end one of them?

 

[NealsComp]

Microsoft says...

Check this link-

http://support.microsoft.com/?kbid=314056

It is a required process

 

[SCHUMIinSA]

Thanks, that's what I thought.