Python Identifiers

Variables are examples of identifiers. Identifiers are names given to identify something. There are some rules you have to follow for naming identifiers:

 The first character of the identifier must be a letter of the alphabet (upper or lowercase) or an underscore ('_').

 The rest of the identifier name can consist of letters (upper or lowercase), underscores ('_') or digits (0-9).

 Identifier names are case-sensitive. For example, myname and myName are not the same. Note the lowercase n in the former and the uppercase N in te latter.

 Examples of valid identifier names are i, __my_name, name_23 and a1b2_c3.

 Examples of invalid identifier names are 2things, this is spaced out and my-name.