Natural hair is hair that has not been straightened using chemical relaxers.
Black people all naturally have very curly or kinky hair. Traditionally black communities worldwide have aspired to have straight hair. This was initially achieved by using very hot metal combs; however, in the early 1970s, hair straightening chemicals known as "relaxers" were made commercially available and became the norm.
Where there are black people you will almost always find boxed chemical relaxers or "creamy crack" as some in the African-American community like to call relaxers. Relaxers are not addictive in themselves but usage of them has tended to be.
In recent times, there has been a large movement of people rejecting relaxers and maintaining their "natural" coily or kinky hair. The decision to stop using hair relaxers and to maintain natural hair is called "going natural."
The reasons for going natural are manifold: some do it "just because", others go natural for a change in hairstyle or because they feel that prolonged use of relaxers has caused damage to their hair and yet others do it as a way to reject Eurocentric standards of beauty and embrace a more diverse Afrocentric take on beauty.
Those with natural hair categorize it using a number and letter system. Most black people fall into the categories 3C, 4A, 4B, and 4C. Completely straight hair as found on some Asian and Caucasian heads is type 1 - this is the only category that is not subdivided by the letters A, B and C.
The higher the number and the letter the more coily or kinky the hair is. Hair that is classified within the same category will tend to respond in a similar fashion to given styling methods and to specific products. These categories serve only as a guide as a single head can have several "types" of hair on it.
Natural haired people do sometimes straighten their hair for variety but always using a temporary method such as a blow dryer and ceramic straighteners. Once the hair is re-wet it reverts back to its naturally coily or curly state.
The large swathes of people that have made the decision to go natural are referred to as being in the "natural hair community". If a year could be placed on when "going natural" went mainstream or became very popular it would probably be 2009 in the USA and perhaps 2011/2012 in the UK. There were many people going natural prior to these years, however, in 2009 in particular many "naturals" took to YouTube and began documenting their "natural hair journey" through video logs or vlogs.
Many black girls have never had to manage their natural hair. As soon as their mother allowed it, they would start using relaxer. The corollary of this is that many people have to learn how to deal with curly hair from scratch. Natural hair behaves very differently to relaxed hair. The knowledge gap is now being filled by the many blogs and vlogs that can easily be found on the web.
The natural hair movement has led to some conflict within the black community as some see it as being divisive. Some naturals see their decision to go natural as being almost spiritual and as such they do try to convince those with relaxed hair to go natural as well.