Researching Variable Naming Rules

Visual Basic
You must use a letter as the first character.
You can't use a space, period (.), exclamation mark (!), or the characters @, &, $, # in the name.
Name can't exceed 255 characters in length.
Generally, you shouldn't use any names that are the same as the functions, statements, and methods in Visual Basic. You end up shadowing the same keywords in the language. To use an intrinsic language function, statement, or method that conflicts with an assigned name, you must explicitly identify it. Precede the intrinsic function, statement, or method name with the name of the associated type library. For example, if you have a variable called Left, you can only invoke the Left function using VBA.Left.
You can't repeat names within the same level of scope. For example, you can't declare two variables named age within the same procedure. However, you can declare a private variable named age and a procedure-level variable named age within the same module.

Python

 Must begin with a letter (a - z, A - B) or underscore (_)
 Other characters can be letters, numbers or _
 Case Sensitive
 Can be any (reasonable) length
 There are some reserved words which you cannot use as a variable name because Python uses them for other things.- See more at: http://www.w3resource.com/python/python-variable.php#sthash.5AXuVlWN.dpuf

Java

Variable names are case-sensitive. A variable's name can be any legal identifier — an unlimited-length sequence of Unicode letters and digits, beginning with a letter, the dollar sign "$", or the underscore character "_". The convention, however, is to always begin your variable names with a letter, not "$" or "_". Additionally, the dollar sign character, by convention, is never used at all. You may find some situations where auto-generated names will contain the dollar sign, but your