A programming language reference (or language reference manual) is an artifact that describes a programming language so that users and developers can understand the basic elements of and write computer programs in the target language.
A programming language reference manual is one form of documentation that is associated with most mainstream programming languages. A reference manual is ordinarily separate and distinct from a programming language specification, which is usually more detailed and intended for use by implementors of the language itself, rather than those who simply use the language to accomplish some processing task.
References
Programming language reference Wikipedia(Text) CC BY-SA