A computer is an electronic machine that works by sequentially reading a set of instructions that make it perform logical and arithmetic operations on binary numbers.
Upon power up, a computer runs, one after the other instructions which are read, manipulate, and then write a set of data accessible to him. Tests and conditional jumps can change following statement, and therefore act differently depending on the data or needs of the moment.
To manipulate the data are obtained either by reading memoirs, by the reading of interface components (devices) that represent external physical data into binary values (moving a mouse button pressed on a keyboard, temperature, speed, compression ...). Once used, or handled, the data is written, either in memory or in components that can transform a binary value by a physical action (write to a printer or on a monitor, acceleration or braking of a vehicle, change temperature of a furnace ...).
The computer can also respond to disruptions that allow it to run programs of specific responses to each, then resume the sequential execution of the interrupted program.
The current technology of computers dates to the mid-twentieth century. They can be classified according to several criteria1 (scope, size or architecture).