According to Hinduism, sex is an integral part of life. It is not a taboo. In fact, it is part of the four Purusharthas of life. Dharma, Artha, Kama, and Moksha are the four Purusharthas of a Hindu’s life. The Kama here means all the activities, which give us pleasure. Sex is also one of those activities.
Kamasutra is the oldest book about the sex written by Vatsayana, a Hindu sage. This book gives detailed descriptions about sex like types, positions, importance, compatibility of partners, eunuchs, etc.
The ancient Khajuraho Temple in India is famous for the sculptures on it in which the statues of men and women are depicted as having sex in different positions.
According to Hinduism, sex is sacred only if it is marital. Hinduism prohibits premarital or extramarital sex.
Some sects in Hinduism worship Yoni (female genitalia) as the Goddess.
Hindus worship Lord Shiva in the form of Lingam, which is a symbol of male creative energy, and is always shown with Yoni, the symbol of female creative energy.
In ancient India, a widow without children was allowed to have sex with the appropriate person in order to have a child. This process was called as Niyoga.
In Mahabharata, Draupadi is depicted as having five husbands who were Pandavas.
Though Hinduism does not support prostitution, you will find prostitutes in all parts of India. Sex without marriage is a bad Karma and the person has to pay the price for it.