This video by Carlos Bueno below depicts in slow-motion what happens when one computer requests an image from another computer over the Internet. I think it’s really neat.
Imagine that the big grey circle on the left is your computer and the circle on the right is some website that you visited. Each flying circle represents a unit of data called a packet. The small green circles represent control packets. The larger blue ones are data packets. In this case it’s an image broken down into many tiny parts.
The exchange begins with a handshake that establishes the rules for communication. We then see a slow ramping up of data being transferred between machines before the full speed download begins. While you watch the video, it might help to imagine the following conversation taking place.
Client: "Hey, Server. Are you there?"
Server: "Yup. I'm here."
Client: "Can you give me that image of a cat playing the piano?"
Server: "I've received your request. Okay. Here's some of the image of a cat playing the piano."
Client: "Got it!"
Server: "Great. Here's some more of the image".
Client "Got it!"
…and so on.
Many thanks to Aaron Hicks for his technical knowledge and fine narration of a hypothetical exchange between machines.
[vimeo width=”651″ height=”488″]http://vimeo.com/14439742[/vimeo]