Tokens are the smallest unit of a programming language. In Java, tokens include keywords, identifiers, literals, and operators. Keywords are reserved words that cannot be used as identifiers. They are used to identify the type of data or operation being performed. For example, int is a keyword that indicates an integer value. Identifiers are used to name variables, methods, and classes.   Literals are Fixed values that are assigned to variables. They cannot be changed during program execution. For example, the number 10 is a literal. Operators perform operations on operands. They can be either unary or binary operators. Unary operators operate on a single operand; binary operators operate on two operands. For example, the + operator is a binary operator that adds two operands together.