A computer manipulates data consistent with instructions of a stored program. Stored program means that the data and program are stored in same memory unit. Central processing unit (CPU) performs the bulk of data processing operations. It has 3 main components:

1.  A set of registers for keeping binary information. 

2.  An 'Arithmetic and logic unit' also referred by (ALU) for performing data manipulation

3.  A control unit also called as CUwhich controls and coordinates the different operations and initiates appropriate sequence of micro-operations for every task. 

Computer instructions are generally stored in consecutive memory locations and are executed in sequence one by one. Control unit permits reading of an instruction from a specific address in memory and executes it with help of Register and ALU.