The file transfer protocol (FTP) allows a user on any computer to get files from another computer, or to send files to another computer. Security is handled by requiring the user to specify a user name and password for the other computer. FTP, File Transfer Protocol is a utility that you run any time you want to access a file on another system.
The network terminal protocol (TELNET) allows a user to log in on any other computer on the network. You start a remote session by specifying a computer to connect to. From that time until you finish the session, anything you type is sent to the other computer. Note that you are really still talking to your own computer. Every character you type is sent directly to the other system. The remote system will ask you to log in and give a password, in whatever manner it would normally ask a user who had just dialed it up.
This allows you to send messages to users on other computers. The computer mail system is simply a way for you to add a message to another user's mail file. These services should be present in any implementation of TCP/IP, except that micro-oriented implementations may not support computer mail.
This allows a system to access files on another computer in a somewhat more closely integrated fashion than FTP. A network file system provides the illusion that disks or other devices from one system are directly connected to other systems. There is no need to use a special network utility to access a file on another system.
This allows you to access printers on other computers as if they were directly attached to yours.
This allows you to request that a particular program be run on a different computer. This is useful when you can do most of your work on a small computer, but a few tasks require the resources of a larger system.
In large installations, there are a number of different collections of names that have to be managed. This includes users and their passwords, names and network addresses for computers, and accounts.
Many installations no longer connect terminals directly to computers. Instead they connect them to terminal servers. A terminal server is simply a small computer that only knows how to run telnet (or some other protocol to do remote login).
Until recently, high- performance graphics programs had to execute on a computer that had a bit-mapped graphics screen directly attached to it. Network window systems allow a program to use a display on a different computer.
