Glossary

Preprocessor

// Example
#include <stdio.h>

Preprocessors are a way of making text processing with your C program before they are actually compiled. Before the actual compilation of every C program it is passed through a Preprocessor. The Preprocessor looks through the program trying to find out specific instructions called Preprocessor directives that it can understand. All Preprocessor directives begin with the # (hash) symbol. These transformations are lexical, meaning that the output of the preprocessor is still text. (Source)