A token is the smallest element of a C++ program that the compiler understands. The C++ parser recognizes the following tokens: Keywords. Identifiers. Literals for numbers, Booleans, and pointers. A token is defined as the program’s smallest individual unit. Tokens in C are classified into five categories. To generate tokens, the C compiler parses the source code. Tokens are classified into five types: keywords, identifiers, operators, special symbols, and constants.