An alphabet or vocabulary of a language is a finite set of symbols in which sentences in the language are written. A symbol is an atomic entity in the language. It is not composed of smaller components. The set of strings of length greater than zero composed of 0 and 1 . The rules for constructing sentences of the language are called syntax rules or production rules or productions .
Terminals are symbols that are in the language.
Nonterminals are names used in the grammar for parts of the syntax. The production rules describe how nonterminals in the syntax of the language are constructed from terminals and other nonterminals. The semantics of a language is a description of what sentences in the language mean. It is much more difficult to express the semantics of a language than it is to express the syntax. This is a question about the syntax of English.