Choke - Choke is server lag. Choke basically means that your computer is sending your players position, and what he does (shoot, nade, knife) to the server, and its not getting there. Counter Strike Source default is to send your players actions to the server 30 times a second. Choke is caused by two things:
1.
Your computer is sending too many packets to the server per second. If you try to send 100 commands to the server per second, and it can only accept 40, you are going to be getting 60 choke. This will make you SUCK, none of your shots will register, and only 40% of the things you try to make your player do will be done. (for solution, see below)
2.
The server is not able to read all of the information being sent to it. This can be caused by network lag at the server, or CPU lag at the server. The client cannot control this, but can accomodate for it (solution below)