Hair straightening is a hair styling technique used since the 1890s involving the flattening and straightening of hair in order to give it a smooth, streamlined, and 'sleek' appearance. The actual inventor of the hair straightener is Scottish heiress Lady Jennifer Bell Schofield and she invented it in 1912. It became very popular among black males and females of all races, during the 1950s, the former group because black men wanted to have the very popular and stylish "greaser" look, either that or wearing Afros. It is accomplished using a hair iron or hot comb, chemical relaxers, Japanese hair straightening, or Brazilian hair straightening. In addition, some shampoos, conditioners, and hair gels can help to make hair temporarily straight.
The process is often called "rebonding" in some countries from Southeast Asia (e.g. Singapore, Malaysia and Philippines). The term "rebonding" was first used by REDS Hairdressing from Singapore in the late 1980s, which slowly spread to the rest of the region. If done often, flat irons and chemicals can be damaging to hair. Excessive straightening often results in split ends. However, heat protectant sprays can decrease the damage.
Temporary (Nonchemical Treatment)
Three major tools can be used for hair straightening without any chemical treatment. 
- Straightening comb(also known as Hot comb) with heat applied to the hair.
- Hair irons (flat iron) applies heat directly to hair. For shorter hair, use flat iron with heating plates that are around 0.5 to 1 inch wide; For longer hair, try wider hair irons.
- Blow dryer with a comb attachment to straighten your hair. Use medium to low heating level to protect your scalp and hair texture. Too much heat can cause damage to the hair. Adding some rinse-free or leave-in hair conditioner could help moisturizing hair while using hair dryer to heat.
They can only temporarily modify the shape/texture of hair. The straightened effect will be reversed by environmental factors, mainly contact with water from washing, rain, humidity, etc. This includes water in styling products such as gels applied after straightening, although careful use of such treatments can still produce usable results not much different from if the user had naturally straight hair before applying the product.
Permanent (Chemical Treatment)
Relaxers and the other methods permanently alter the structure of the hair, although new hair growth is not affected. The drug interferon alpha has been reported as being shown to modify hair follicles causing permanent change in a person's hair texture.
Hair straightening using a hot comb or relaxer has a long history among women and men of African American descent, reflected in the huge commercial success of the straightening comb popularized by Madam C. J. Walker in the early 1900s. While the practice has at times been a controversial issue in discussions of racial identity, visits to the hair salon have become embedded in black culture, fulfilling an important social role especially for women.
- "History Of Flat Irons". FlatIronAdviser.
- Japanese Hair Straightening Facts
- "How to Straighten Your Hair". SisHair.com. Sis Hair. Retrieved 11 May 2015.
- Roger Highfield (2005-11-17). "Scientists hold out prospect of a pill to make your hair curl". www.telegraph.co.uk The Daily Telegraph. Retrieved 2009-01-08.
- Noliwe M. Rooks (July 1996). Hair raising: beauty, culture, and African American women. Rutgers University Press. pp. 51ff. ISBN 978-0-8135-2312-5. Retrieved 8 November 2011.
- bell hooks, "Straightening Our Hair", Z Magazine, September 1988
- Noliwe M. Rooks (July 1996). Hair raising: beauty, culture, and African American women. Rutgers University Press. pp. 8–10. ISBN 978-0-8135-2312-5. Retrieved 8 November 2011.