Networking

I understand that TCP Reno cuts its congestion window in half when it receives a triple duplicate ACK, and that it also cuts the window down to 1 segment when it times out. But why does it do this?

Why do you need 6 acknowledgements for 1 piece of data being sent only once? Are you trying to crash the server? Congestion hits critical mass when you get hit that hard. The only direction is down. Just like the gas price crisis in America.
http://news.yahoo.com/u-gas-prices-crash-140433859.html

But TCP Reno calls for that behavior when triple duplicate ACKs are received or when a timeout occurs. I just want to know why because all I can rationalize is that when a timeout occurs, the congestion window needs to be cleared to receive the retransmission of the data that was lost.

The part about triple duplicate ACKs is what I don't understand. Why decrease it by only half?