what is a reserved word, or keyword
In a computer language, a reserved word is a word that cannot be used as an identifier, such as the name of a variable, function, or label â it is reserved from use. This is a syntactic definition, and a reserved word may have no meaning. A closely related and often conflated notion is a keyword, which is a word with special meaning in a particular context. This is a semantic definition. By contrast, names in a standard library but not built into the language are not considered reserved ...