Modular programming consists of separating implementation from interface and hiding information in the implementation. In C this is achieved by placing the interface definition in a header file and the implementation in a source file. Disciplined use of static is used to hide implementation details.

Modular programming in C involves breaking down a program into separate modules or units of functionality, promoting code organization, reusability, and maintainability. It allows for encapsulation of internal details, easier collaboration among developers, and focused testing and debugging.

Modular programming entails isolating the implementation from the interface and concealing information within the implementation. In C, the interface definition is placed in a header file, while the implementation is placed in a source file.