Each of these three classifications encompasses a set of network services. Perhaps the most popular service to emerge from the networking phenomenon has been E-mail. E-mail allows a user to send an electronic message to a target user's electronic mailbox. When this mail is posted, it is usually possible to address the message to more than one user. A bulletin board is a form of asynchronous conferencing which allows a single user to communicate with a large base of users over a network.
Bulletin boards act as a filing system for a sender.
The sender's message is sent to the bulletin board and stored in a file folder by subject type. The message can then be read by the network members if they are interested. The bulletin board is a rudimentary single machine conferencing system and has some of the benefits of E-mail and conferencing in a package. The computer mediated system can control the large number of people by ensuring that only one person has the floor at a time. Tele-presence gives conference participants the feeling of being in the same room with one another.