Grammars (vyākaraṇas) concern the description of speech forms (śabda) considered to be correct (sādhu) through derivation and thereby serve to make understood the usage found in the Vedas. The grammar that was granted the status of a Vedāṅga is that of Pāṇini. This work is referred to in toto as a śabdānuśāsana (means of instruction of correct speech forms); since the core of Pāṇini's work comprises the eight chapters of sūtras that serve to describe both the current language of his time and features particular to Vedic, it also bears the name Aṣṭādhyāyī.