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 −
All identifiers should begin with a letter (A to Z or a to z), currency character ($) or an underscore (_).
After the first character, identifiers can have any combination of characters.
A key word cannot be used as an identifier.
Most importantly, identifiers are case sensitive.
Examples of legal identifiers: age, $salary, _value, __1_value.
Examples of illegal identifiers: 123abc, -salary.