The basic and smallest unit of a C program is called C tokens.
There are six types of token in C:
Keywords are reserved words whose meaning is predefined by the programming language specification. They convey some special meaning in programming and we must not use them for other purposes. They are basically a sequence of characters that have fixed to mean for example break, for, while, do-while, do, if, int, long, char.
Identifiers are names for entities in a C program, such as variables, arrays, functions, structures, unions and labels. An identifier can be composed only of uppercase, lowercase letters, underscore and digits, but should only start with an alphabet or an underscore.
Constants are the most fundamental and essential part of the C programming language. Constants in C are the fixed values that are used in a program, and its value remains the same during the entire execution of the program.
Variables: A variable is nothing but a name given to a storage area that our programs can Basically, a variable used to store some form of data. Different types of variables require different amounts of memory.
Strings are defined as an array of characters. The difference between a character array and a string is the string is terminated with a special character ‘\0’.
Operator is a symbol that operates on a value or a variable. For example + is an operator to perform addition. C has a wide range of operators to perform various operations.