Macros in C

Macros in C are preprocessor directives that define constant values or reusable code snippets, improving code efficiency and readability. Defined using the #define directive, they replace specified identifiers with their values or code before compilation. Macros can be simple constants or more complex, parameterized snippets. For example, defining a constant for the value of pi or creating inline functions to avoid function call overhead. However, macros do not provide type checking and can lead to errors if not used carefully. They are a powerful tool but should be used judiciously to maintain code clarity and correctness.