The three domains - Orthography, Orthoepy and Grammar - are central to the definition of a standard language

They are finite and highly rule-governed

There are only so many sounds and letters, and the ways in which they combine to produce syllables and words are also limited

There are only so many ways in which words vary their grammatical shape

There are only so many ways in which words are arranged into sentences

Children normally complete the learning of their phonology and grammar by the time they reach puberty