A P2P app then, is an application that allows peers to communicate directly with one another. There are two common P2P apps. The first are Instant Messagers, such as Microsoft s Messenger Service and America Online s ICQ, which allow users to transfer text messages and files to one another instantaneously. The other is Napster, which lets users exchange MP3s from one remote computer to another, without going through a central agent. E-mail is electronically transmitted mail.
Snail mail is slang for postal mail.
The snail reference highlights the slowness in sending something through the postal service, rather than through e-mail, which is almost instantaneous. A network consists of several computers connected together. Networked computers generally can pass information from one to another with the help of a server. A server is a software program or hardware device that transfers information to one or more computers. In the computer world, when something is down , it means that it is out of commission and cannot be used for the moment.