Sikhism is a monotheistic faith that originated in India during the 15th century. Today, it has roughly 20 million adherents worldwide, the majority of whom live in the Punjab, in northwest India. It was founded by Guru Nanak, the first in a line of ten gurus (spiritual leaders) who developed and promulgated the faith. In Punjabi, the word "Sikh" means "disciple" and the faithful are those who follow the writings and teachings of the Ten Gurus, which are set down in the holy book, the "Adi Granth."
Sikhism synthesizes elements of both Islam and Hinduism into a distinct religious tradition. Like Islam, it emphasizes belief in only one God and similar to Hinduism, teaches that the karmic cycle of rebirths cannot be overcome unless you achieve oneness with God. For Sikhs, everyone is equal before God and a good life is achieved by remembering God at all times, being part of a community, serving others, living honestly, and rejecting blind rituals and superstitions.
In the late 17th century the tenth guru, Gobind Singh, established a military brotherhood within Sikhism called the Khalsa (fraternity of the pure). Although not all Sikhs belong to the Khalsa, many obey its edict of wearing the five symbols of faith, the Five Ks: uncut hair (kesh), a wooden comb (kanga), a steel bracelet (kara), cotton undergarments (kachera), and a sword (kirpan). The turban worn by Sikh men is the most visible manifestation of their adherence to these principles.
From Sikhism, PBSOnline, accessed 16/04/2016, <http://www.pbs.org/thestoryofindia/gallery/photos/14.html#sikhism>