The oldest continuously-practiced religion in the world, and the dominant religion of South Asia (chiefly, India of course), the Indonesian island of Bali, and certain parts of The Caribbean (such as many areas of Guyana or Trinidad) due to the presence of Indo-Caribbean people there, Hinduism's roots can be traced back to Iron Age India, and as such it is believed to be the oldest living religion in the world. Contrary to popular Western belief, most modern Hindus will attest that it is monotheistic, not polytheistic. To sum it up simply, in the same way Catholicism has the concept of the Father, Son, and Holy Spirit being different forms of the same God, Hinduism has a similar belief: Vishnu, Lakshmi, Lord Shiva, Bramha, Hanuman, etc. are all different forms of one God, known variously as Brahma, Ishvara, or other names. So, though Hindu Mythology contains a vast pantheon of gods and beings, they are all recognized to be part of the same Sarvasva or "All-Being", i.e, God. In fact, there is a passage in the Bhagavad Gita (one of the long sequence of religious texts in the Hindu faith) where Krishna explicitly encourages religious tolerance, stressing that all gods are in fact part of one supreme God. The Supreme God Vishnu demonstrates this to the warrior Arjuna by allowing Arjuna to see, for a moment, Vishnu's Universe-encompassing form (Vishwa rupa), which Arjuna promptly begs Vishnu to stop because Arjuna cannot grasp the true form. It should be noted though, that Hinduism encompasses a wide range of beliefs and is not bound by a single doctrine. There is no one leader of the religion, equivalent to the Pope or the Dalai Lama, so there are different sects of the religion with different dogmas. Hinduism is also very loose and allows acceptance of other religions; the practice of Hinduic ideals and beliefs, known as Sanadhana Dharma, is defined as "a way of life", and not a religion. For this reason, the very concept of conversion does not exist in any of the Hindu texts, and those that wish to convert to Hinduic faith can actually do so with no ceremony, and can even keep practising faith in another religion. (However, due to modern-day inter-religious tensions, this cannot be stated as a general sentiment, and there is a significant minority that holds on to the belief that you have to be born Hindu to be Hindu.) This makes Hinduism the only major world religion that is henotheistic by nature, i.e, involving devotion to one God while accepting the existence of others. This is why most Hindu sects do not seek converts, as there is an accepted belief that the goals of spiritual life can be attained through any religion, as long as it is practiced sincerely. It is also one of the only religions in the world that allows the practice of atheism within itself. It is also common practice for a community to hold faith in a "local" god, associated with a single temple or location. On occasion these may not even have temples or even idols or statues; it might merely be the concept of a higher being, usually a protector and usually named after the location, that is believed in by the local population, with no particular rituals or prayers. Prayer locations of these deities are usually sacred groves, and there are thousands of such locations and gods scattered across India. Activities like logging and hunting are heavily prohibited in and around these areas, enforced by a combination of tradition, religious beliefs and the law. Because of this, over the years, these groves have become a haven for both rare animals and plants, as species seek shelter in them due to habitat destruction. This enrichment of flora and fauna has only added to their legend; Wikipedia actually has a page on these. As is evident from the description so far, the information provided here by no means summarizes the entirety of Hindu beliefs; as it is easily the most complex religion in the history of the world. Because of the wide range of traditions and ideas incorporated within it or covered by it, even hardcore Hindus will have trouble coming up with a definition for the word "Hinduism" itself. Buddhism is an offshoot from Hinduism, in the same way that Christianity and Islam are offshoots from Judaism.
HINDU GODS & MYTHOLOGYMain article: Hindu Mythology According to Hindu Mythology, the universe was born from Lord Brahma, The Creator, and it is maintained by Lord Vishnu, The Preserver, and governed by Shiva, The Supreme God. Shiva is also known as The Destroyer, in the sense that after the age of man is over, the world will be destroyed to unite all individual souls with the Supreme Consciousness. The three together form the Great Trinity, more popularly known as the "Trimurti"* of Hinduism. Both Vishnu and Shiva are widely popular among Hindus as deities, to the point that there has been some friction between the devotees of the two. Vishnu is arguably the better known, probably because of the vast amount of mythology surrounding Vishnu and his Avatars. Since the maintenance of the world is his responsibility, Vishnu will incarnate as an Avatar whenever Evil rises, to bring balance to the world. Prince Ram, Lord Krishna and Vamana are some of the popular incarnations of Vishnu. Ram's story has been chronicled in the Ramayana, and Krishna's in the Mahabharata, a part of which is the Bhagavad Gita. Apart from the Trinity, there are also a number of younger gods or Devas, who occupy the heaven, known as Swarga. Almost every entity in nature has a corresponding god or goddess - Agni (Fire), Vayu (Wind/Air), Varuna (Water & Sky), Surya (Sun), Chandra (Moon), Bhumi (Earth), etc. Indra is the King of the Gods, and Lord of Swargaloka, which is heaven. Narakaloka is the opposite, and is hell. Naraka, however, has no Lord. The concept of the Devil, i.e; a central being that causes all evil, does not appear in Hinduism. Simply put, such a character simply doesn't exist in the mythology. Instead, Hinduism states that good and evil exist inside all creatures, and, according to the path one chooses, his fate will be determined. This is where Karma comes into play - in accordance with your actions, in your next life you will be born as a lesser or higher being. Though demonic creatures do exist in mythology, even they are never portrayed as Always Chaotic Evil - even Ravana, the biggest, baddest Big Bad in the entire Hindu mythos, never comes off as a Complete Monster, though he is definitely crazy. Other noteworthy characters include Hanuman, The Pandavas, Drona, Bhishma, Narada, and Balarama. See the main article for more details, and for the significance of the Om symbol. Countries where Hinduism is very popular: