Billions of dollars are spent each year by black women in America, Africa and elsewhere, to make their hair do what they want it to do.
The strong chemicals used to straighten hair can cause damage and the treatment can be expensive, so is straight hair really "good hair"?
A new film by the American comedian Chris Rock reveals the extraordinary lengths some women go to.
The BBC's Christine Otieno, who does not straighten her hair, went to a hair salon in the Kenyan capital Nairobi, to hear why some women do.
Hannah Pool is a journalist of Eritrean origin who had not straightened her hair until recently and Margot Rodway Brown runs an organisation called Adornment, which advises black women on how they can wear their hair natural.
In conversation with Newshour's Robin Lustig, they describe how they are wearing their hair at the moment.
First broadcast 28 October 2009