Remote Procedure Calls in unity with Unet?

Guys I am bit confused about these calls. I know the basic understanding of it but can someone please explain them a bit. Following are the calls I am confused about.
[Client]
[Server]
[ClientRpc]
[Server]

I want to clear things a bit. I was taking em wrong. Every Script that is networked and is on server end behaves as a server part. All players that are Spawned over a network has a server part and a client part.
I was misunderstood about that.
So
[Server]
Command runs all functions at server side
[Client] on all client instance of that object or script
and
[Command] is a call to server from the client
and [ClientRpc] is a call to all clients of that object from the server.