For questions on the god of preservation, among the Trimurti. Also called Narayana. The Supreme God or Brahman in Vaishnavism. In case of questions exclusively on his avataras, the respective tag is preferable like Rama, Krishna.
1. Guidelines for using the tag
For questions about Lord Vishnu, the god of preservation this tag must be used. In case of questions on directly any of his famous avataras (without any other link to Vishnu) like Rama and Krishna, their respective tag must be preferred. The tag Narayana also redirects to this tag and hence this is the preferred tag.
2. General Description
Lord Vishnu (Sanskrit: विष्णु), also known as Narayana, is one of the three primary gods (Trimurti). Being the god of preservation, he has a dominance of Sattvaguna. His divine consort is Devi Lakshmi, the goddess of fortune. Together they reside in Vaikuntha where the Lord rests on a bed made by the coils of his serpent, Shesha or Ananta, earning him the name of Anantashayana.
For Vaishnavas, he is the Supreme God or Brahman, the all omnipotent, omniscient deity.
The deity is described as being blue like the Atasi flower or like rain clouds. He has four hands in which he holds a conch (shankkha), discus ( sudarshana chakra), mace (kaumudaki gada) and a lotus. He is draped in yellow garments and adorned by the Vaijayanti Mala and Kaustubha gem. It is from his navel that Brahma in a lotus sprang out at the beginning of the Padma Kalpa and hence he is known as Padmanabha. The Lord’s vehicle is the ever faithful eagle Garuda, the Lord of Birds and son of Vinata.
Being the god of preservation, the Lord protects the earth from evil and it is for this purpose that he manifests in different forms on earth. As the Srimad Bhagavad Gita 4.7-8 says:
यदा यदा हि धर्मस्य ग्लानिर्भवति भारत। अभ्युत्थानमधर्मस्य तदाऽऽत्मानं सृजाम्यहम्॥७॥
परित्राणाय साधूनां विनाशाय च दुष्कृताम्। धर्मसंस्थापनार्थाय संभवामि युगे युगे॥८॥Whenever there is decline of righteousness, O Arjuna, and rise of unrighteousness, then I manifest Myself. For the protection of the good, for the destruction of the wicked and for the establishment of righteousness, I am born in every age.
The Srimad Bhagavatam describes about 24 main such avatars of the Lord with Rama and Krishna being the most famous and widely adored deities.