Java's UDP description

[iago]

The UDP protocol provides for communication that is not guaranteed between two applications on the network. UDP is not connection-based like TCP. Rather, it sends independent packets of data from one application to another. Sending datagrams is much like sending a letter through the mail service: The order of delivery is not important and is not guaranteed, and each message is independent of any others.

Also, like the postal service, UDP tends to lose packets or send them to the void.  I think their analogy is very apt

[Yoni]

While explaining the differences between TCP and UDP to a friend a year or so ago I came up with this analogy: TCP is like a telephone (connection, stream, reliable), UDP is like a walkie-talkie (connectionless, datagram, unreliable).

The guy I explained it to later asked the same question in a job interview, used my analogy to explain it and got the job.

[iago]

While explaining the differences between TCP and UDP to a friend a year or so ago I came up with this analogy: TCP is like a telephone (connection, stream, reliable), UDP is like a walkie-talkie (connectionless, datagram, unreliable).

The guy I explained it to later asked the same question in a job interview, used my analogy to explain it and got the job.

haha, nice.  If I'm ever asked, I'm honestly going to give the postal service analogy.  "unreliable, gets lost, etc"