Timesharing was developed because a large computer system costs hundreds of dollars per minute to operate. Thus, an individual could not engage in a rewarding working session sitting directly at a large computer, which was dedicated to that user, without enormous waste. Humans work slowly compared with computers. Consequently, the computer would be idle most of the time waiting for the user to initiate some action.
Timesharing was designed to make that kind of direct use efficient by enabling a computer to serve many users simultaneously. With such a system, each user sits at a terminal. The computer transfers its attention rapidly from one user to another, performing work as needed. Information is processed so quickly that the computer, in effect, appears to be totally dedicated to the work of each user.
Once the concept of timesharing computing was developed, it became apparent that users did not have to be in the same room as the machine, but could communicate with it over telecommunication lines from any place in the world.