I'm not sure what your asking here. I'm going to assume that you mean how fast can data be sent over the Internet.
There are several parts to this. First of all, the speed of the sending and recieving computers. The faster they can process, then the more data tehy can send or recieve at once.
Then there's the connection. If you are using a modem, then that will tell you the speed. A 56K modem can trasmit and recieve at 56Kbps, but rarely attains this, due to the next part.
The line connecting you to the internet also can limit speed, especially over a phone line, which is why ADSL is becoming the new standard.
If i'm off on the wrong track, or if anyone notices any glaring mistakes in this, let me know.
Scotsdude