In Java, tokens are the smallest individual units of a program that have meaning to the compiler and are used to represent the various elements of a program, such as keywords, identifiers, operators, and literals. Tokens are the basic building blocks of a Java program and are the smallest unit of a program. The Java compiler breaks the line of code into text (words) called Java tokens, which are the smallest element of the Java program. The different types of Java tokens include:

• Keywords: These are reserved words that have a specific meaning in the Java language. Examples of keywords in Java include class, public, private, if, else, while, for, switch, case, break, continue, return, and static, among others.

• Identifiers: These are names given to variables, methods, classes, and interfaces in a Java program. Identifiers must follow certain rules, such as starting with a letter, underscore, or dollar sign, and not being a keyword.

• Constants: These are values that do not change during the execution of a program. Constants may belong to any of the data types.

• Special Symbols: These are symbols used in Java having some special meaning and thus, cannot be used for some other purpose. Examples of special symbols include brackets, parentheses, and curly braces.

• Operators: These are symbols used to perform operations on operands, such as arithmetic operations, logical operations, relational operations, and assignment operations.

• Separators: These are symbols used to separate tokens in a Java program. Examples of separators include commas, semicolons, and periods.

When a Java program is compiled, the compiler breaks it down into a sequence of tokens, which are then translated into Java bytecode and executed inside the interpreted Java environment.