Modularity specifies to the division of software into separate modules which are differently named and addressed and are integrated later on in to obtain the completely functional software.

It is the only property that allows a program to be intellectually manageable. Single large programs are difficult to understand and read due to a large number of reference variables, control paths, global variables, etc.

• It allows large programs to be written by several or different people
• It encourages the creation of commonly used routines to be placed in the library and used by other programs.
• It simplifies the overlay procedure of loading a large program into main storage.
• It provides more checkpoints to measure progress.
• It provides a framework for complete testing, more accessible to test
• It produced the well designed and more readable program.