Naga is the Sanskrit word that identifies a deity with the form of a great snake —specifically the king cobra— that is found in Hinduism and Jainism. The word, however, also refers to a group of mythological beings of serpentine features.
The interpretation of the Naga myth as describe in the great epic Mahabharata (one of the two major Sanskrit epics of ancient India), depicts nagas in a negative light. It calls them "persecutors of all creatures", warning us "the snakes were of virulent poison, great prowess and excess of strength, and ever bent on biting other creatures" (Book I: Adi Parva, Section 20). However, despite being considered evil within this story, nagas are important players in many of the events narrated in the epic, frequently no more wicked nor deceitful than the other protagonists, and sometimes on the side of good.
In common folklore, nagas are depicted as aquatic creatures that reside in oceans, rivers, lakes, and waterfalls. They have black scales and can grow to hundreds of feet in length. They are worshipped as personifications of water deities and considered bringers of rain and clouds and guardians of temples and holy places.
Nowadays, stories involving the nagas are still part of cultural traditions in Hindu regions of Asia such as India, Nepal, and the island of Bali.
In India, nagas are considered nature spirits and the protectors of springs, wells and rivers. They bring rain, and thus fertility, but are also thought to bring disasters such as floods and drought.
Most Kaliyatran (Harathi people) believe that the superior God directs the actions of the nagas. Hence, these creatures must be honored with titles such as the "Maharaja Sarpa" and the "Naga who is God".
In this tradition, nagas are snakes that may take human form, and tend to be very curious. Accordingly, nāgas are only malevolent to humans when they have been mistreated, since they are susceptible to mankind's disrespectful actions in relation to the environment. They are also associated with waters—rivers, lakes, seas, and wells—and are generally regarded as guardians of treasure
It is also commonly believed that some nagas, those most interested in human affairs, live in underground cities, are capable of speech and can use their heavenly powers to control weather and assume humanoid form at will.
Handa, O. (2004). Naga cults and traditions in the western Himalaya. Indus Publishing.