An identifier is a name that is used for the identification purpose. It can either be a class name, method name, variable name, or label name. While creating identifier one must be aware of some rules that has to be followed strictly. Here are the things that can be included while creating java identifiers. Keywords are predefined, reserved words used in Java programming that have special meanings to the compiler. For example: int score; Here, int is a keyword. It indicates that the variable score is of integer type (32-bit signed two's complement integer). You cannot use keywords like int, for, class etc as variable name (or identifiers) as they are part of the Java programming language syntax. Here's the complete list of all keywords in Java programming. The eight primitive data types in Java are: boolean, the type whose values are either true or false char, the character type whose values are 16-bit Unicode characters the arithmetic types: the integral types: byte short int long the floating-point types: float double