Head shaving can be performed by most standard razors or electric hair clippers. Several companies produce razors designed specifically for head shaving. Because it is generally hard to shave long pieces of hair, people with longer hair cut their hair short using scissors before shaving it. Incidents of cutting one's scalp with a razor blade are common, but generally are avoidable if precautions are taken. Using an electric shaver generally results in fewer cuts.
Head shaving has been done for practical, religious, cultural, or aesthetic reasons. Practical reasons include work safety or comfort, lice prevention, grooming simplicity and preparation for surgery. Competitive swimmers will sometimes shave their heads to reduce drag while swimming. Cultural reasons may include an emphasis on conformity and solidarity as identical haircuts can make diverse crowds look very similar, or as part of hazing rituals. Many Buddhists, Hajj pilgrims, skinheads and Vaisnavas, especially members of the Hare Krishna movement, shave their heads.
The practice of head shaving has often been used to punish people, such as criminals or political opponents. Especially for women, the act of shaving off an offender's hair serves to humiliate the victim and remind them of their offense. For example, thousands of European women had their heads shaved in front of cheering crowds in the wake of World War II, as punishment for associating with occupying Nazis during the war. As of 2006, several countries — such as the United States, Libya and Russia — still shaved the heads of prison inmates as a punishment, and also to prevent the spread of lice. Inmates of boot camps for delinquent youths in the USA are forced to have their heads shaven. Cancer supporters get their head shaved to raise money for a cancer patient who is having chemotherapy.
The practice of shaving heads has been used in the military, mostly for new recruits. The militaries of the United States, Russia and several other countries have welcomed their recruits by giving them haircuts using hair clippers with no guard attached. As of 2006, shaved heads continued to be standard haircuts in the United States Marine Corps and the United States Army. In Greece, this practice was abolished on June 25, 1982, when the military started allowing recruits to have up to 4 cm of hair. Before then, the regulation haircut in the Greek army for recruits was en hro (an archaic phrase for "shaved to the bone"), which was implemented for hygiene reasons. Shaved heads also emphasise a strict, disciplined and masculine persona, hence its use in the military and in many sports.
In some Hindu societies, Widows are required to shave their heads upon the death of their husbands. Buddhist monks and nuns shave their heads upon entering their order, and Korean Buddhist monks and nuns have their heads shaved every 15 days.. Muslim men are recommended to shave their heads after the pilgrimage of Hajj as it is three times more rewarding than clipping the hair short.
In the 1960s, some British working class youths developed the skinhead subculture, whose members were distinguished by short cropped hair (although at that time they didn't shave their heads right down to the scalp). This look was partly influenced by the Jamaican rude boy style. It was not until the skinhead revival in the late 1970s — with the appearance of punk rock-influenced Oi! skinheads — that many skinheads started shaving their hair right down. Head shaving has also appeared in other youth-oriented subcultures, such as the punk, hardcore, metalcore, Nu metal, hip hop and techno music scenes.