Turban is an inseparable part of a Sikh's life. Since Guru Nanak, the founder of Sikhism, all Sikhs have been sporting a turban. Refer to Dr. Trilochan Singh's Biography of Guru Nanak. All Sikh Gurus sported turban. The Sikh Rehat Maryada (Sikh Code of Conduct) specifically says that all Sikhs must wear a turban. According to the Rehatnama, compiled after a few years of Guru Gobind Singh's demise, the five Kakars of Sikhism were: Kachh (a knee-length underwear), Karha (a iron bangle), Kirpan (a sword), Kangha (comb) and Keski (a small turban).

Guru Gobind Singh is quoted as saying:
Kangha dono vakt kar, paag chune kar bandhai
kMGw donoN vkq kr, p`g cuMn kr bMDwey]
Translation:
Comb your hair twice a day and tie your turban carefully, turn by turn.

Bhai Chaupa Singh writes:
Kachh, karha, kirpan, kangha, keski, Eh panj kakar rehat dhare Sikh soi.
k`C, kVw, ikRpwn, kMGw, kyskI, ieh pMj kkwr rihq Dry is`K soie]
Translation:
The five Kakars of Sikhism are, knee-length underwear, iron bangle, sword, comb, and small turban. A person who wears all these Sikh symbols should be considered a Sikh.Several old Sikh documents refer to the order of Guru Gobind Singh about wearing five Ks. Bhai Rattan Singh Bhangu is one of the most famous old Sikh historians. He is the author of Sri Gur Panth Parkash" which he wrote almost one and half century ago.

He writes:
"Doi vele utth bandhyo dastare, pahar aatth rakhyo shastar sambhare
Kesan ki kijo pritpal, nah(i) ustran se katyo vaal"
doeyN vyly auT bWiDE dsqwr, pihr AwT rwiKE Ssqr sMBwr]
kysn kI kIjo ipRqpwl, nwih ausqrn sy kwitE vwl]
Translation:
"Tie your turban twice a day and carefully wear weapons 24 hours a day
Take good care of your hair. Do not cut your hair. (Sri Gur Panth Parkash by Bhai Rattan Singh Bhangu, page 78)

Holiness and SpiritualityTurban is a symbol of spirituality in Sikhism. Guru Angad honored Guru Amardas with a turban (Siropa) when he was seated, as the Guru. The most revered Sikh symbol is hair. The turban is required by every Sikh in order to cover his / her hair. This is the primary reason the comb (kangha) is one of the five basic requirements of the Sikh way of life. The turban (Dastaar) has remained the key aspect of a Sikh's honour. Those who have selflessly served the community are honoured with turbans. Initiation ceremony is the most important ceremony in a Sikh's life. That ceremony cannot be complete without the injunction of always wearing a turban. Indeed, a short-turban (called a keski) is one of the five requirements of initiated Sikhs.

All Sikh Gurus sported turban. Throughout our short history, all Sikhs also sported turbans. The turban has become synonymous with Sikhism. Yet, other religions such as Hinduism, Islam and even Christianity have similar tenets as evidenced by the following:

Once they enter the gates of the inner Court, they are to wear linen vestments. They shall wear linen turbans, and linen drawers on their loins. (Old Testament: Ezekiel 44:18-19)