Many Hindus practice a number of everyday rituals meant to keep believers mindful of divinity in their lives. Most Hindus have shrines in their home that are dedicated to the particular form of Brahman (the self-existent eternal being) they choose to worship. For example, a Hindu may choose to worship Brahman in the form of Vishu or Shiva. In rituals conducted at home shrines, devotees often lights a lamp or make small offerings of food before a murti, an image believed to be an embodiment of a divinity. Hindus also recite scripture, perform ablution in sacred rivers, sing devotional hymns, meditate, and chant mantras. Most Hindus visit temples only during religious festivals.Though the practice is not mandatory, many Hindus also perform pilgrimages to various holy cities. The caste system, which has some basis in Hindu scripture, assigns people to strict social classes and duties. Although it is outlawed in India, it remains a powerful cultural and social force.