Hair straightening works by altering the structure of the hair using heat or chemicals. Heat-based methods, such as flat irons, work by breaking down the hydrogen bonds in the hair shaft, allowing the hair to be reshaped temporarily. Chemical methods, like keratin treatments or relaxers, modify the hair’s natural bonds to achieve straightness. These processes can provide sleek, smooth hair, but it’s essential to use heat protectants and follow proper aftercare to maintain hair health and minimize damage.