FTP is used to establish a session with remote hosts to download (or upload) files. Downloading files means transferring a file resident on a remote host to the local computer. Uploading files means transferring files from a local computer to a remote host.

FTP uses some of the services of TELNET to establish a session. TELNET services are needed to allow users to view directories on remote hosts and navigate around the host to find files. However, users cannot run applications on remote hosts using FTP.

Two sessions are needed to run FTP. One session is used for sending control information (such as TELNET commands). The other session is used for the actual transfer of data files. This allows files to be transferred without interruption, while still allowing control information to be sent to the remote host.

FTP supports several data types. Files can be transferred in ASCII or EBCDIC formats. These file types are used when transferring text files. Files from word processors and desktop publishing applications cannot be sent using these formats because they include proprietary characters not supported by ASCII or EBCDIC. If files of this nature are transferred using ASCII or EBCDIC, they will be unintelligible because the formatting characters are only recognized by the application that created them. All formatting characters will be translated into ASCII text, which will result in a lot of garbage.

For all other file types (including word-processed or desktop publishing files) FTP supports binary file...