Wikipedia
Narayana ( Sanskrit: Nārāyaṇa) is the Vedic Supreme God according to Vedas, Itihasas, Bhagavata Purana and Other Puranas (including his different avatars) in Hinduism, venerated as the Supreme Being in Vaishnavism. He is also known as Vishnu and Hari and is venerated as Purushottama or Supreme Purusha in Hindu sacred texts such as the Bhagavad Gita, the Vedas and the Puranas.
Narayana is the name of God in his infinite all pervading form. Narayana is one of the names of Vishnu (and sometimes Krisna). He is the Supreme Purusha of Purusha Sukta. The Puranas present a seemingly divergent, but accurate description of Narayana (as an Enlightened Supreme Being). The fifth verse of the Narayana Sukta, a hymn in Yajurveda, states that Narayana pervades whatever is seen or heard in this universe from inside and outside alike. Another important translation of Narayana is The One who rests on Water. The waters are called narah, [for] the waters are, indeed, produced by Nara-Narayana (the first Being); as they were his first residence [ayana], he is called Narayana. In Sanskrit, "Nara" can also refer to all human beings or living entities (Jivas). Therefore, another meaning of Narayana is Resting place for all living entities. The close association of Narayana with water explains the frequent depiction of Narayana in Hindu art as standing or sitting on an ocean.
In Hindu sacred texts like Vedas, Puranas etc., Narayana is described as having the divine blue colour of water-filled clouds, four-armed, holding a Padma (lotus flower), mace Kaumodaki, Panchajanya shankha (conch) and a discus weapon Sudarshana Chakra. Narayana is also described in the Bhagavad Gita as having a 'Universal Form' (Vishvarupa) Vishvarupa which is beyond the ordinary limits of human perception or imagination.
Bhagavata Purana declares Narayana as Para Brahman Supreme Lord who creates unlimited universes and enters each one of them as Lord of Universe. Narayana engages in creation of 14 worlds within the universe as Brahma when he deliberately accepts rajas guna. Narayana himself sustains, maintains and preserves the universe as Vishnu when he accepts sattva guna and annihilates the universe at the end of maha-kalpa as Shiva or Rudra when he accepts tamas guna. According to this reference, the holy Trimurti is non-different from Narayana.
Narayana is also venerated as Mukunda which means God who is giver of mukti or Moksha or liberation from cycle of births and deaths in the material world.
Narayana's eternal and supreme abode beyond the material universe is Vaikuntha which is a realm of bliss and happiness. It is also known as Paramapadha, which means final or highest place for liberated souls, where they enjoy bliss and happiness for eternity in the company of supreme lord. Vaikuntha is situated beyond the material universe and hence, cannot be perceived or measured by material science or logic. Sometimes, Ksheera Sagara where Narayana or Vishnu rests on Ananta Shesha is also perceived as local Vaikuntha with in the material universe.
In the Mahabharata, Krishna is often referred to as Narayana and Arjuna as Nara. The epic identifies them both in plural 'Krishnas', or as part incarnations of the earlier incarnations of Vishnu, recalling their mystical identity as Nara-Narayana.