For many years, researchers have been able to use computer facilities from remote hosts. What makes the computer networks more attractive today is that the different networks are interlinked, the telecommunication infrastructure more powerful and that the publicly available information sources are growing each day. As a consequence, it is of less importance to which academic network a researcher is connected. For example, Internet and Bitnet offer access to electronic mailing functions which allows the users to send and receive messages worldwide.
Additionally, the MAIL command supports the subscription to topic-oriented electronic bulletin boards or discussion lists. Two other main functions of the Internet with its TCP/IP standards are FTP and TELNET. FTP stands for "file transfer protocol" and helps to exchange binary or ASCII files between two computers. TELNET is the command for accessing a remote host in an interactive way. The following examples should clarify somewhat the different applications which are related to these TCP/IP commands.