Beliefs and practices
The sikha or shikha (śikhā) is a Sanskrit word that refers to a long tuft, or lock of hair left on top or on the back of the shaven head of a male Orthodox Hindu. Though traditionally all Hindus were required to wear a śikhā, today it is seen mainly among Brahmacharya, 'celibate monks' and temple priests.
How it is done
Traditionally, Hindu men shave off all their hair as a child in a saṃskāra or ritual known as the Mundan ceremony, or chudakarana, chudakarma. A lock of hair is left at the crown (Brahmarandhra). Unlike most other eastern cultures (including ancient Egypt) where a coming-of-age ceremony removed childhood locks of hair similar to the śikhā (e.g. a forelock or pigtails in China, a topknot in Thailand, a sidelock in Egypt etc.) in India this prepubescent hairstyle is left to grow throughout the man's life, though usually only the most orthodox religious men will continue this hairstyle.
The śikhā is tied back or knotted to perform religious rites. Only funerals and death anniversaries are performed with the śikhā untied or with dishevelled hair. Dishevelled hair is considered inauspicious, and represents times of great sorrow or calamity. In Hindu scripture, Draupadi took an oath in the assembly of the Kurus after she was molested by Dussasana that she would remain with dishevelled hair until the enemies were properly revenged. Similarly, Chanakya is said to have taken an oath to leave his Shikha untied until he humbles the Nanda kings who insulted him.
Tying a śikhā as done in South India
The Tamil word for śikhā is kudumi and traditionally it is represented in two styles. The most common kudumi (called Pin Kudumi) is identical to the śikhā, with a knotted lock of hair on the crown of the head and the rest of the hair shaved off.
Mun-Kudumi is a style where the hair is grown long in the front and knotted to the forehead. This hairstyle was popular amongst certain South Indian Brahmin sects (Dikshitar, Namboothiris), and the ruling class of Kerala (Nairs).
The technique used to tie the hair into a Kudumi is as follows: The lengthy hair can be tied with the help of left thumb and index fingers. You roll up the lock of hair over the left thumb and index fingers put together by your right hand till you reach the tail end. Then hold the tail end of hair by the left thumb and index fingers and pull out the fingers with the tail end of the hair. You get the knot. After some little practice you will get a tight and neat knot.
The śikhā reportedly signifies one-pointed (ekanta) focus on a spiritual goal, and devotion to God. It is also said that the śikhā allows God to easily pull one to paradise, although this belief is unsubstantiated and maybe a more islamic belief (see 'Similar hairstyles' below). According to Smriti Shastras it is mandatory for all Hindus to keep sikha and the first three twice-born or dvija castes to wear yajnopavita, also called janeu or paita (sacred thread).
In his autobiography, Mohandas K. Gandhi writes about his encounter with an orthodox Hindu: "He was pained to miss the shikha (tuft of hair) on my head and the sacred thread about my neck and said: 'It pains me to see you, a believing Hindu, going without a sacred thread and the shikha. These are the two external symbols of Hinduism and every Hindu ought to wear them.' ... [T]he shikha was considered obligatory by elders. On the eve of my going to England, however, I got rid of the shikha, lest when I was bareheaded it should expose me to ridicule and make me look, as I then thought, a barbarian in the eyes of the Englishmen. In fact this cowardly feeling carried me so far that in South Africa I got my cousin Chhaganlal Gandhi, who was religiously wearing the shikha, to do away with it. I feared that it might come in the way of his public work and so, even at the risk of paining him, I made him get rid of it. "(WikiSource)
In western counties, the śikhā hairstyle is often seen worn by adherents of the Hare Krishna movement.
As stated above, the belief that the śikhā "allows God to easily pull one to paradise" may in fact be an islamic, or at least an Arabian superstition, as the following passages may illustrate:
Sir Thomas Herbert, 1st Baronet (1606 – 1682) described a similar hairstyle worn by Persians in his book 'Travels in Persia': "The Persians allow no part of their body hair except the upper lip, which they wear long and thick and turning downwards; as also a lock upon the crown of the head, by which they are made to believe their Prophet will at Resurrection lift them into paradise. Elsewhere their head is shaven or made incapable of hair by the oil dowae (daway) being thrice anointed. This had been made the mode of the Oriental people since the pomulgation of the alcoran (Al Quran), introduced and first imposed by the Arabians."
In 'Passages of Eastern Travel', Harper's magazine, 1856, p.197, an American traveller wrote: "All Arabs, men and boys, have their heads shaved, leaving only a scalp lock, said by some to be left in imitation of the Prophet, who wore his his own thus; and by others said to be for the convenience of the angel who will pull them out of the graves when the day of rising shall come."
Riffian (Berber) men of Morocco had the custom of shaving the head but leaving a single lock of hair on either the crown, left, or right side of the head, so that the angel Azrael is able "...to pull them up to heaven of the Last Day." 
The oseledets, or khokhol hairstyle of the Ukrainian Cossacks, or Zaporozhians, is near identical to the śikhā. The scalplock of many Native American tribes (particularly of the eastern woodlands, such as the Huron) is very similar in appearance to the śikhā, although, like the Cossack oseledets, a much different meaning was applied to this hairstyle.
The śikhā may also be referred to as 'choti', 'kudumi' or 'chuda'. It should not be confused with the rattail (haircut) nor the mullet hairstyle, both popularized in the 1980s.
- A Concise Encyclopedia of Hinduism, Klaus K. Klostermaier, ISBN 1-85168-175-2
- Daily Life In Ancient India, Jeannine Auboyer, ISBN 1-84212-591-5, P. 164-5
- Converting women: gender and Protestant Christianity in colonial South India, Eliza F. Kent, Page 227
- Bhāgavata Purāṇa 6.8.8
- Bhāgavata Purāṇa 6.19.7
- Passages of Eastern Travel, Harper's magazine, 1856, p.197, http://books.google.com.au
- El Maghreg: 1200 Miles' Ride Through Morocco, Hugh Edward Millington Stutfield
- Ian Heath "The Vikings (Elite 3)", Osprey Publishing 1985; ISBN 9780850455656, p.60
- David Nicolle "Armies of Medieval Russia 750–1250 (Men-at-Arms 333)" Osprey Publishing 1999; ISBN 9781855328488, p.44
- Vernadsky 276–277.
- A Pictorial History of The American Indian, Oliver Lafarge
-  An excellent website for further information on śikhā.
-  An ISKCON handbook for monks of Krsna.
-  A deity with śikhā from Nevali Cori.
-  A boy with śikhā, sculpture, Notre Dame, France.
-  A Vaishnava with śikhā.
-  Ukrainian cossack with the śikhā-like oseledets.