• Identifier cannot be a keyword.
• Identifiers are case-sensitive.
• It can have a sequence of letters and digits. However, it must begin with a letter, $ or _.
The first letter of an identifier cannot be a digit.
• It's convention to start an identifier with a letter rather and $ or _.
• Whitespaces are not allowed.
• Similarly, you cannot use symbols such as @, #, and so on.
Here are some valid identifiers:
• score
• level
• highest Score
• number1
• convert To String
Here are some invalid identifiers:
• class
• float
