Shikshā is one of the Vēdāngas that is given by Maharshi Pānnini. In this Vēdānga Pānnini explains the pronunciation of alphabets, place of origin of alphabets, and the stress applied in the pronunciation. There are 86 theorems in this Shikshā Vēdānga. In order to pronounce the Mantras in a proper way, this Vēdānga is written by Pānnini. The pronunciation of alphabets in Sanskritam is scientific in nature. That means the pronunciation is related to the development of health of the person who is talking and who is listening.
AshTādhyāyi is the Vyākaranna (grammar) of the Sanskritam language. There are 8 chapters in this Vēdānga and that is why it is called “AshTādhyāyi”. This Vēdānga has 4,000 theorems. These theorems explore the relation between the “Shabda” (sound) and “Artha” (meaning) of the words in Mantras. This Vēdānga gives the production of the “Shabda”, gives “Svarūpam” (the real nature) of the word, and dictates the meaning of the word. If Vēda is considered as a human body, then AshTādhyāyi is the face of Vēda.
In Rigvēda (4-58-3), Vyākaranna is praised as follows:
देवता - अग्निः सूर्यो वाऽपो वा गावो वा घृतं वा ऋषिः - वामदेवः छन्दः - भुरिक्पङ्क्तिः स्वरः – पञ्चमः
च॒त्वारि॒ शृङ्गा॒ त्रयो॑ अस्य॒ पादा॒ द्वे शी॒र्षे स॒प्त हस्ता॑सो अस्य । त्रिधा॑ ब॒द्धो वृ॑ष॒भो रो॑रवीति म॒हो दे॒वो मर्त्याँ॒ आ वि॑वेश॥३॥
If Vyākaranna is considered as a “वृ॑ष॒भ” (Ox) then it has four शृङ्गा॒ (horns) – nāma (noun), Ākhyātha (verb), Upasarga, and Nipātha. It has three “पादा॒” (feet) – Varthamāna (present), Bhūta (past), Bhavishyath (future). It has two “शी॒र्षे” (head) – Sup and Ting. It has “स॒प्त हस्ता॑सो” (seven hands) – seven Vibhaktis. The Svarūpam of Vyākaranna is fixed in the “वृ॑ष॒भ” (Ox) “Urassu” (chest), “KanTam” (throat), and “Shirassu” (head).
This Chandas Shastra is called as the Pāda (feet) of Vēda. As a human stands on his/her feet, similarly Vēda Mantra stands on the Chandas. The chanting of Vēda Mantra without error and with harmony it requires Chandas. With the help of Chandas we can know how many letters are used in a Mantra and in what order they are used. Chandas also helps in knowing the meaning of the Mantra. In Vēdas we have different names for this Chandas depending upon the number of letters present in the Mantra. The names of the Chandas and the number of letters used in the Mantra are given as – Gayatri (24), Ushnnik (28), Anushtup (32), Brihati (36), Pankti (40), Trishtup (44), Jagathi (48), Athijagathi (52), Shakvari (56), Athishakvari (76), Krithi (80), Prakrithi (84), Ākrithi (88), Vikrithi (92), Samskrithi (96), Abhikrithi (100), Uthkrithi (104).
Niruktham means Nirvachanam (Definition). The Shastra that fulfills the Nirvachanam of the words is called Niruktham. Normally the definition of the word is primary, and the word is secondary. Therefore, we can say Niruktham is the filler of Vyākaranna. Niruktham is written by Maharshi Yaska and contains explanations for 734 Mantras and 32 Shākhā Mantras. Niruktham is also called as commentary to Nighantu. To give the Vyutpatti (etymology) of Shabda (sound of word) is the aim of Niruktham. Nighantu consists of definitions of difficult words from Vēdas.
To know about Sūrya (Sun), Graha (Planets), Nakshatra (Stars) and other interstellar bodies, one must study Jyōthishyam. Entire Astronomy is based on this Jyōthishya Shāstra. What is light? What is the path of this light? Is there a boundary for light? How many types of light are there? What is the size of Sūrya (Sun), Graha (Planets), Nakshatra (Stars)? What is the distance between them? All such details are explained in this Jyōthishya Shāstra. This Shāstra gives extraordinary details of creation because of knowing the Nakshatra through this Shāstra.
The Vihita Karma (Yajna) that is described in Vēdas is explained in this Kalpa Shāstra. Those who want to do Yajnas can learn this Shāstra and learn the Mantras that are to be used in the Yajnas. This Shāstra is completely in Sūthra (theorem) format and contains details of Shroutha Sūthras, Grhya Sūthras, Dharma Sūthras, and Shulba Sūthras. Shroutha Sūthras gives the summary of different Yajnas, their purposes, and their uses. Grhya Sūthras explain the duties of married persons. It explains the Shōdasha Samskārās, and Pancha mahā Yajnas. Dharma Sūthras explain the duties of Varnnāshramas, social principles, Government and Public Dharma, Family relations, division of properties, daily duties etc.