A hair relaxer is a chemical product used to straighten curly or wavy hair. It works by breaking down the protein structure of the hair, allowing it to be reshaped into a straighter form. Hair relaxers are commonly used by individuals with naturally curly hair who desire a smoother, more manageable look. There are two main types of hair relaxers: lye and no-lye. Lye relaxers contain sodium hydroxide, while no-lye relaxers use calcium hydroxide or guanidine hydroxide. Both types can cause damage if not used properly, so it's important to follow instructions and consider professional application for best results.