A header file is a file with extension .h which contains C function declarations and macro definitions to be shared between several source files. There are two types of header files: the files that the programmer writes and the files that comes with your compiler.

In C++, header files are used to reduce the amount of code that needs to be written.

The Standard C Library has 19 header files.

The h file extension is used for all files.

The complexity and amount of lines of code are both reduced.

Additionally, it allows you to reuse the functions that are declared in header files for various purposes.

A header file is a file that contains declarations, macro definitions, and other information that is shared between multiple source code files. Header files typically have a .h extension and are included at the beginning of C source files using the #include directive. The primary purpose of header files is to provide a way to share common definitions, function prototypes, and other declarations across multiple C source files.