Sex (being a man or a woman) is a protected characteristic in the Equality Act 2010.
Sex inequality can affect both women and men, but women are affected more often than men.
The Equality Act 2010 also covers gender reassignment discrimination. The Act says that you must not be discriminated against because you are transsexual - that is, your gender identity differs from the gender assigned to you at birth.
The Act also specifically covers pregnancy discrimination and sexual harassment.