Brahmāṇḍa — The Cosmic Egg and the Structure of Creation
Brahmāṇḍa (brahma = vast, Brahman, pertaining to Brahmā the creator; aṇḍa = egg; 'the Brahman-egg' or 'the egg of Brahmā') is the Purāṇic conception of the entire manifest universe as a single cosmic egg — a bounded, structured totality within which all created existence is contained. At the beginning of each kalpa (cosmic cycle, approximately 4.32 billion years), Bhagavān produces the Brahmāṇḍa from His līlā-vibhūti (the realm of cosmic play/creation) through His śakti (power/energy): first the five mahābhūtas (great elements — ākāśa/space, vāyu/air, agni/fire, āpaḥ/water, pṛthvī/earth) come into being in successive layers, then Brahmā the creator is born from Bhagavān's navel lotus and fashions the interior of the cosmic egg into the hierarchical system of worlds.
The fourteen worlds (caturdaśa-loka) within the Brahmāṇḍa, as described in detail in the Bhāgavata Purāṇa (Book 5) and the Viṣṇu Purāṇa, are arranged in two groups. Below the Earth (Bhū-loka) are seven descending nether worlds: Atala, Vitala, Sutala, Talātala, Mahātala, Rasātala, and Pātāla — realms of increasingly powerful but non-liberated beings (nāgas, asuras, and the like). Above the Earth are seven ascending worlds: Bhū-loka (Earth), Bhuvar-loka (the atmospheric realm, home of lesser devas and departed souls in transit), Svar-loka (Indra's heaven), Mahar-loka (realm of the great sages who survive the partial dissolution), Jana-loka (realm of Brahmā's sons — Sanaka, Sanandana, Sanātana, Sanatkumāra), Tapas-loka (realm of those who practice supreme austerity), and Satya-loka or Brahma-loka (Brahmā's realm at the summit, the highest world within the Brahmāṇḍa). At each cosmic dissolution (pralaya), these worlds are folded back into Bhagavān's body.
The critical Śrī Vaiṣṇava theological point about the Brahmāṇḍa is that Vaikuṇṭha — Bhagavān's eternal residence — is not part of the Brahmāṇḍa at all. Vaikuṇṭha is nitya-vibhūti (the eternal domain), entirely distinct from the līlā-vibhūti (the created cosmos). While the Brahmāṇḍa is created, sustained, and dissolved, Vaikuṇṭha never undergoes any modification — it is the eternal, unchanging realm of perfection where Bhagavān resides with His nitya-sūris and muktas. The Nālaṭiyār Divya Prabandham traditions and the Āchārya commentaries emphasize that the seeker's aspiration should not be for any world within the Brahmāṇḍa (including Brahma-loka, which is impermanent) but for Vaikuṇṭha — the realm beyond all creation that never comes to an end.