External subroutines are used for tasks that more than one program is likely to want performed : for example, calculating a square root.

An early stage in the devloment of structured programing.A program is broken down in to pieces,or modules which can be coded and tested separately.

Operations performed on output to be printed to make it easier for a human being to read and understand, such as inserting commas and decimal points, suppressing leading zeros, and including dollar sign.

A collection of techniques for the planing and writing of programs that increases programmer productivity,e.g.,top-down programing and the use of loop,selection and sequence structures.

A portion of the computer in which data, instructions. and the results of processing can be stored.