Hinduism is the religion of the majority of people in India (80%) and Nepal, with a significant number of followers also residing outside of the subcontinent. There are over 900 million Hindus worldwide. It is the world's third most popular religion, after Islam and Christianity.
Hinduism is not easy to define, in many ways. It's practice varies greatly across its adherents and there is no defined Holy Scripture unlike most other religions, no founder and no agreed fundamental practices. It's closely associated with other Indian religions such as Jainism Buddhism and Sikhism and in many ways is the world's oldest living religion, as many of it's practices stretch back thousands of years. Because so many key figures have added philosophies and writing over time, many find it useful to refer to Hinduism as a family of religions or a way of life. The word 'Hindu' probably does not go back beyond the 15th or 16th century and likely developed as a way for the people of the region to differentiate themselves from their Muslim neighbors.
Hinduism originated around the Indus Valley, near what is now modern Pakistan. There is no official starting date of the religion and beliefs and practices have changed and molded with the social and political changes of the time, i.e. the rise and falls of various kingdoms and migration. Commonly held core Hindu beliefs include Atman, the eternal self, often referred to the spirit, or soul. Thus Hinduism encourages asterism to enable viewing oneself as a spiritual being, rather than simply material. Dharma is an important term in many Indian religions, like Buddhism, and in Hinduism it means 'duty', virtue' and even religion, and is the power that upholds the universe and society. Dharma gives us the power to act as virtuous, moral beings, but how to do so is not concrete and depends on our age, gender, social status and other factors. This personal Dharma is called 'sva-dharma'. Hindus believe that acting in accordance with Dharma is a gift to humanity and God.
Varna is an important Hindu concept that determines the personal Dharma and has played a large role in creating the caste system, still evident in Indian society. Karma is a Sanskrit word that means 'action' and is a law that means every action has a consequence in the immediate or later future. Good actions in accordance with Dharma will have good responses, and bad actions that go against Dharma will have negative ones. Bad Karma will not only have ramifications in this lifetime but in the next life because of reincarnation, a process called Samsara. Samsara is a continuous cycle of rebirth, and humans can reap their rewards in this life, a future human rebirth or be born into a heavenly or hellish realm. After death Hindus believe that the soul is transported to another body, animal, human or divine and the goal of liberation (moshka) is to be free from this endless cycle.
Purushartha is a doctrine that recognizes the needs of humans, and that they are legitimate even if they differ based on the person's context, which include sexual pleasure, profit or success. The main Hindu texts are the Vedas, which they believe were written by scholars directly from God, and passed through generations through word of mouth. They were gifted to India through the Aryans. The Bhagavad Gita is one of the most popular Hindu texts, and the world's longest poem, composed between 500BCE and 100 BCE. It recounts the tale of the wars of the house of Bharata as a story of triumph of good over evil.
Speaking generally, Hindus place importance on the good treatment and wellbeing of animals. The cow is revered by Hindus, and killing them is illegal in India. No Hindu would eat them and many Hindus are fully vegetarian. Some temples have holy animals and many deities have the heads or features of animals, like Ganesh and jobs like butchery are only awarded to the lowest caste. Ahisma is one of the ideals of Hinduism and strongly emphasized by the political icon Gandhi. It means that we should avoid harming or wanting to bring harm to any living thing and is not exclusive to violence- it includes all harm such as mental or emotional. Being such an old religion, Hinduism has some of the earliest teachings about peace, which can be seen in the Rig Veda>. God or Bhagavan is conceptualized in two meanings; as an impersonal energy, beyond language and identical to the soul, and as a compassionate loving person.
Hinduism has a seemingly endless range of denominations but the three most popular are the Vaishnavas, Shaktas and Shaivas, each with a focus on their chosen God form. Vaishnavas believe that God incarnates into this world in various forms like Krishna and Rama, with a focus on Vishnu. Shaivas focus on Shiva and his performance of the five acts of creation, maintenance, destruction, concealing himself, revealing himself through grace. Shaktas focus on the Goddess and her gentler (Lakshmi, Sarasvati) forms or more ferocious (Durka and Kali).
Yoga is a Hindu tradition in which practitioners perform a series of postures, exercises and focus on breathing to discipline the mind and body.
Gurus or Acharyas are teachers or masters of tradition, who convey wisdom and knowledge and act as examples to their disciples. When the Guru dies the tradition is passed on to one or more successors who can carry on or multiply the tradition, and in some cases they can become the subject of extreme devotion.
Because of the wide, diverse spectrum of Hindu belief there are a plethora of festivals observed. The most well-known, also celebrated by Jains and Sikhs is the festival of lights, Diwali. It extends over 5 days and celebrates the triumph of good over evil, light over darkness and knowledge over ignorance, though the accompanying myths and legends vary depending on what part of India it is being celebrated in, and involves fireworks and sweets, so is popular with children.