Shiksha (Devanagari: शिक्षा IAST: śikṣā) is one of the six Vedangas, treating the traditional Hindu science of phonetics and phonology of Sanskrit. Its aim is the teaching of the correct pronunciation of the Vedic hymns and mantras. The oldest phonetic textbooks are the Pratishakyas (prātiśākhya, a vrddhi abstract from Sanskrit prati-śākhā), describing pronunciation, intonation of Sanskrit, as well as the Sanskrit rules of sandhi (word combination), specific to individual schools or Shakhas of the Vedas.