Reserved word
From Wikipedia, the free encyclopedia
In computer programming languages, a reserved word is a word which has a special grammatical meaning to a language and cannot be used as an identifier in that language.
For instance, in SQL, a user cannot be called "group" because the word group is used to indicate that an identifier refers to a group, not a user. Such a word is a keyword; it is because its use is restricted that it is also a reserved word.
Sometimes the specification for a programming language will have reserved words that are intended for possible use in future versions. In Java, const
and goto
are reserved words — they have no meaning in Java but they also cannot be used as identifiers. By "reserving" the terms, they can be implemented in future versions of Java without "breaking" older Java source code.