Can you explain what a linker is and what role it plays in program compilation?

The linker is a program that combines compiled object files (.o) and libraries into a single executable or library. Its main task is to resolve external references, that is, to link function calls and variable accesses to their actual memory addresses.

When building a program, the compiler converts source code into object files, but references to functions and variables from other files remain undefined. The linker finds these symbols, links them, and creates the final executable file.

For example, if a function foo() is declared in one file and called in another, the linker ensures that the call to foo() points to the correct implementation address.

Thus, the linker plays a key role in the build process, integrating all parts of the program into a single whole.