(CNN) Here's a look at Hinduism, the world's third largest religion after Christianity and Islam . "Hinduism" is derived from a Sanskrit word that means "dwellers by the Indus River."

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Beliefs/Practices

There is no single founder or founding incident of Hinduism. It grew out of cultural and religious changes in India.

The Hindu belief is that gods or divinities can take many forms, but all form one universal spirit called Brahman. The three most important representations of Brahman are Brahma, the creator of the universe, Vishnu, the preserver of the universe, and Shiva, the destroyer of the universe.

The Hindu belief involves reincarnation of the soul, which is rebirth after death. Hindus believe the conditions of one's present life are due to karma or accumulated good or bad behavior in past lives.

One improves one's conditions through good behavior and creates suffering for oneself through bad behavior. Eventually the soul will achieve moksha, or salvation, and stop the cycle of rebirths to become a part of the absolute soul.

Paths to salvation are called the margas or yogas.

- karma marga - performing social obligations and offering selfless service.

- jnana marga - studying and cultivating an intellectual understanding into one's identity with Brahman.

- bhakti marga - devotion to one's personal god.

- raja or dhyana marga - not as widely recognized as the three outlined in the Bhagavad Gita, this path uses meditation to gain insight into the absolute soul that resides within one's self.

There are multiple sects, theologies, and beliefs in Hinduism, and there is no single book of doctrine. It is an inclusive religious group, allowing for a lot of diversity.

The Vedas are the primary literary works, containing sacred verses and hymns composed in Sanskrit. The Rig Veda was the first of the four Vedas. The Samaveda, Yajurveda and Atharvaveda followed later.

Two other important texts are the Upanishads and the Bhagavad Gita.

Pilgrimages and festivals are common in Hinduism. Diwali, the New Year's celebration, features giving of gifts and lighting of ceremonial lamps. Holi, the Festival of Colors, marks the arrival of spring each year.

India's Caste System

Indian society has traditionally been divided into a hierarchical system called caste or jati, which is not limited to Hindus, but which most Hindus have observed throughout history. It is hereditary and each caste has its own set of values, rules, dietary beliefs, etc. Many do not marry outside their castes.

There are four major varnas or social classes most caste members fall into:

- Brahmans - the priests and other educated professionals.

- Kshatriyas - warriors and those who own a lot of land.

- Vaishyas - formerly the farmers, now those involved in commerce.

- Shudras (some sources say Sudra) - the lowest of the social classes. Made up of laborers, artisans and other servants.

There are some that do not fall into any of these categories, and they are now considered part of the Scheduled Caste. They are lower than the Shudras on the hierarchy, and they are people who perform "unclean" work, such as leather working and street cleaning. They have been called untouchables, Dalits, Harijans or backward castes. Although Hinduism teaches that discrimination and prejudice go against the idea of the divinity of all beings, both sometimes exist within the caste system.

Mahatma Gandhi called these untouchables "children of God." Although the 1950 Indian constitution outlawed "untouchability," violence against them continues

History

2300-1500 BC - A very developed civilization dwells in the Indus Valley with its own religion and culture, and is believed to be the beginnings of Hinduism.

1500 BC - Indo-European language and culture spread into the Indus Valley through a mix of trade and migration.

1500-1200 BC - The Rig Veda is written and is composed of 1,028 hymns devoted to the gods.

800-600 BC - The Brahmans are written and added to the Vedas. They are prose writings that explain certain ceremonies found in the Vedas.

600 BC - The belief in reincarnation develops.

300-650 AD - The worship of images, especially female divinities, becomes common.

800-1800 AD - The most divisive period. Many different schools and sects emerge, and Islam becomes a major influence in India.

1947 - British India is split into what is now India and British India is split into what is now India and Pakistan . Hinduism is now the major religion of India.