data is saves in a computer. A computer processes this data under the control of a program. A computer receives information. A computer input this data or information for late use on disk. A computer input the saved data or information whenever needed. If equipped with a modem and if it is output to a telephone line,the computer may send information to other computers through telecommunication systems. If equipped with a modem and if it is connected to a telephone line, the computer may retrieves information from other computers through telecommunication system.