A distinct character among the four Vedas
Where the Ṛg, Sāma, and Yajur Vedas are closely tied to the formal Śrauta sacrificial ritual, the Atharva Veda is oriented toward everyday concerns: healing the sick, protection from snakebite and sorcery, success in love and business, harmony in family life, and the rites surrounding marriage and death. This practical, domestic character is why some scholars describe it as the earliest textual source for what later developed into Āyurveda, traditional Indian medicine.
The text survives in two recensions: the Śaunakīya (or Śaunaka) recension, the version most commonly meant when "the Atharva Veda" is referenced today, and the Paippalāda recension, whose core is considered by some scholars to be textually earlier than the Śaunakīya, though it survives less completely.
Structure across twenty books
Books 1–7 contain the shorter hymns of charms and spells. Books 8–12 contain early speculative material on the nature of the universe and the self, anticipating the Upaniṣadic turn found more fully in later texts. Books 13–18 address householder concerns — marriage, death, and domestic life. Book 19 is a later addition, and Book 20 — consisting largely of hymns borrowed from the Ṛg Veda — is the latest layer, associated with liturgical use by the Atharvan Brahmán priest.
Associated Upaniṣads
The Atharva Veda is the source of three of the ten or eleven principal (mukhya) Upaniṣads: the Muṇḍaka Upaniṣad (source of the well-known image of two birds on one tree, and the metaphor of the bow and arrow for meditation on Brahman), the Māṇḍūkya Upaniṣad (the shortest of the principal Upaniṣads, its twelve verses analyzing the syllable Oṃ and the four states of consciousness), and the Praśna Upaniṣad (structured as six questions posed by students to a teacher). A very large number of later, minor sectarian Upaniṣads — devoted to specific deities, yogic practices, or renunciate life — are also traditionally attached to this Veda, reflecting its more open, less formally ritual-bound character.
Michael Witzel, "Vedas and Upaniṣads," in The Blackwell Companion to Hinduism (ed. Flood, Blackwell, 2003). Patrick Olivelle, The Early Upaniṣads (Oxford University Press, 1998) — for the Muṇḍaka, Māṇḍūkya, and Praśna Upaniṣads.