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 keyword 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.
A class name should start from a capital case letter and long names should use camel casing. For example: TaxationDepartment
Object name should start from lower case letter and long names should use camel casing. For example: taxationDepartment