India is one of the most religiously diverse nations in the world, with religion playing a central role in the lives of most Indians.

80% of the people in India are Hindus, considered one of the oldest religious and philosophical systems in the world. Islam is practiced by 13.4% of all Indians, Christianity by 2.4%, and Sikhism by 1.86%. Buddhism and Jainism both arose on the Indian subcontinent and have a world-wide presence; in addition, Zoroastrianism and Judaism have a long history in India, but their present-day numbers are small.

http://en.wikipedia.org/wiki/Religion_in_India

Hinduism is supposed to be 'apauruseya', i.e., of impersonal origin & so also are the Gods of Hinduism. They are eternal & though the deities appear to be different & independent, they are really facets of the same Brahman, the Supreme God.

As Sri Ramakrishna says, there can be as many spiritual paths as there are spiritual aspirants & similarly there can really be as many Gods as there are devotees to suit the moods, feelings, emotions & social background of the devotees.

The Hindu scriptures were eloquent while describing the qualities of God. He is all-knowing & all powerful. He is the very personification of justice, love & beauty. He is ever ready to shower His grace, mercy & blessings on His creation.

From the Rig Veda, we come to know of the vedic gods eight Vasus, eleven Rudras, twelve Adityas, Indra & Prajapathi, being the Gods of earth, the heavens & the space.

The main Hindu Gods as we accept today can be broadly classified as Saiva Gods (Siva, His consort, His sons, His other forms), Vaishnava Gods (Vishnu, His consort, His various avatharams) & Sakthi or Saktha (Forms of Goddess Sakthi).  There are other sects such as Ganapathyam (Lord Ganesha, son of Lord Siva),  Kaumaram (Lord Muruga, son of Lord Siva), Souram (Lord Surya).