All Java components require names. Names used for classes, variables, and methods are called identifiers. In Java, there are several points to remember about identifiers. They are as follows -
Step 1 − All identifiers should begin with a letter (A to Z or a to z), currency character ($) or an underscore (_).
Step 2 − After the first character, identifiers can have any combination of characters.
Step 3 − A keyword cannot be used as an identifier.
Step 4 − Most importantly, identifiers are case sensitive.
Step 5 − Examples of legal identifiers: age, $salary, _value, __1_value.
Step 6 − Examples of illegal identifiers: 123abc, -salary.