1 SUMMARY: HISTORY AND EVOLUTION OF COMPUTERS Computers are generally defined as automated machines where data are input, processed and displayed (output product) through adequate devices. They operate according to how they are programmed, whether wrongly or truly. Despite its high intelligence, the human brain is lacking rapidity and capacity to dealing with huge tasks of data processing, thus, a machine that can process big amount of data in a very fast way must be developed to solve the demands in terms of data record and communication as well as information. That was the context in which computers emerged. In other words, they have been invented due to the need to find a device that can supersede the human brain in data processing. Therefore, they become instruments conceived to process huge amount of data, very quickly and accurately. This is what makes them very helpful to human life, especially in the management of all fields of activities. Hence, in an attempt to summarize the development of computers over time, we propose in this analysis to present first the basic components of a computer and its organization/functioning. Thereafter, it seems necessary to provide an outline of the early stage of computers before their breakthrough actually started. Finally, we offer a description of the different generations of computers from early stages up to nowadays. There are different types of computers. At the very beginning, the Mainframe Computer was the model. However, as it was costly and required more staff, it was later superseded by the Minicomputer which offered various software systems for multiple tasks. The Microcomputers appeared afterwards, with the particularity of using microprocessors. The highly used computer nowadays is the Super Computer which is very powerful and adapted for many tasks. Basically, a computer consists of hardware and software. Hardware components describe the physical parts of the computer. Input devices like keyboards, mice, scanners... read in data. Output devices like printers, monitors... present out data to the user. The Central Processing Unit is the heart of the computer system and includes the control unit, the arithmetic and logic unit, and a bus system. There is also the Main Memory (Primary Storage, RAM). The RAM (Read Access Memory) works closely to the CPU and acts as a buffer between CPU and the rest of the computer. RAM operates only when the computer is on and is characterized by its memory’s volatility. However ROM (Read Only Memory) which is non volatile memory keeps data and instructions when power is off. There are also other categories of non-volatile memory viz. PROM (Programmable Read Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM). These previous memories (volatile and non- volatile) are just stocking data and instructions for a temporary period. Hence, in order to stock data and/or information permanently, relevant devices are used.