Bṛhannāradīyapurāṇa is a mahāpurāṇa. It is in 38 chapters. It seems to be the orignal, then its expanded to Nāradīyapurāṇa. (NCC. vol -14 page 88 ). This is a Sātvika purāṇa. Bṛhannāradīyapurāṇa is one of the miner purāṇa of Vaiṣṇava tradition.( Brihannaradiya Purana Part 1 by S.N Khandelval, Chaukhamba krishnadas acadamy page 9–10). The Bṛhannāradīyapurāṇa is a Vaiṣṇava text primarily focused on the praise and worship of Vishnu, often referred to as Narayana, Vasudeva, Hari, or Janardana, but rarely as Kṛiṣna. Before start the purāṇa there is dialogue between Sūta and sages; In the Naimiṣa forest, Śaunaka and many sages practiced austerities and worshipped Viṣṇu with great devotion, some aiming to please him through these practices. They pleased him through either knowledge (Jñāna) or ultimate devotion (Bhakti). Sages had questions about the sacred places, how to achieve liberation ? unwavering devotion to Hari, and the consequences of actions,Śaunaka sent them to Sūta. Sūta, a renowned Parāṇika. At that time he was performing sacrifices to Janardana at siddhāśrama. The sages thanked Śaunaka and went to siddhāśrama, where sūta was performing the Agniṣṭoma sacrifies to Nārāyāṇa. sūta proposed to narrate the Bṛhannāradīyapurāṇa , In which Nārada spoke to Sanatkumāra about Narayana, rooted in vedic thought. (Studies In The Upapuranas Vol-i by Hazra R.C page 309, 310, 311, 312) This manuscript contains only 31st' chapter. This purāṇa deals topics like universe originated from Mahāviṣṇu (Nārāyāṇa) who takes the forms of Prajāpati?, Viṣṇu and Rudra embody the three Gunas (Rajas, Sattva, and Tamas) and also appear as Prakṛiti, Purusha, and Time (kāla), Names of the seven upper worlds (Bhūḥ,Bhavaḥ etc.) and seven lower worlds (Atala, Vitala etc.), devotinal vrata and tithis related with Viṣṇu , Plantaiton of Tulsī.
Devotional literature for different forms of supreme Hindu deity Viṣṇu, Hindu Legends, Purāṇic Literature.