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After deciding on the type, the next thing a programmer must do is decide on a variable name.

A variable name must start with a letter of the alphabet or an underscore. (They can also start with a $ or _ but that is discouraged.)
The best choice is to start each variable name with a lower case letter.
After the first letter, there can be additional letters, digits and underscores.
There cannot be any spaces in a variable name.
Words that have a special meaning in Java such as include or main cannot be used to name variables.
The name of the variable should indicate its purpose. Variable names like a, b and c are not very good names for variables unless you are using them for the three sides of a triangle.
If two words are joined together (you cannot have any spaces), a capital letter for the second word or an underscore can improve the clarity.
Example: hoursWorked, state_tax, and dueDate are all good variable names.
Remember, Java is case sensitive. If a variable is declared as hoursWorked, it must be written exactly the same way each time it is used.
It will be easier to remember the names if you develop a particular style and stick to it.