With udp you send they recieve, done. With tcp you send , they send and aknowledgement and then you say ok and then the transfer starts so there is a three way handshake as opposed to just a send and receive so there is much less overhead which makes things faster. A basic book on ip tcp/ip will explain the whole lot better than i can and in much greater depth try this one , i can't vouch for it as i just pulled it from almighty google http://www.pcsupportadvisor.com/search/c04100.htm