Modularity of OOPS program

The modularity of object-oriented programming means that the valid components of a big program can each be implemented individually. Different people can work on various classes. Each execution task is isolated from the others.

This has benefits, not just for organizing the execution, but for fixing problems afterward. Since implementations are contained within class boundaries, problems that come up are also expected to be isolated. It's easier to track down bugs when they're placed in a well-defined part of the program.