A woman is an adult female human. Prior to adulthood, a female human is referred to as a girl (a female child or adolescent). The plural women is sometimes used in certain phrases such as "women's rights" to denote female humans regardless of age.

Typically, women inherit a pair of X chromosomes, one from each parent, and are capable of pregnancy and giving birth from puberty until menopause. More generally, sex differentiation of the female fetus is governed by the lack of a present, or functioning, SRY-gene on either one of the respective sex chromosomes. Female anatomy is distinguished from male anatomy by the female reproductive system, which includes the ovaries, fallopian tubes, uterus, vagina, and vulva. An adult woman generally has a wider pelvis, broader hips, and larger breasts than an adult man. Women have significantly less facial and other body hair, have a higher body fat composition, and are on average shorter and less muscular than men.

Throughout human history, traditional gender roles have often defined and limited women's activities and opportunities, resulting in gender inequality; many religious doctrines and legal systems stipulate certain rules for women. With restrictions loosening during the 20th century in many societies, women have gained access to careers beyond the traditional homemaker, and the ability to pursue higher education. Violence against women, whether within families or in communities, has a long history and is primarily committed by men. Some women are denied reproductive rights. The movements and ideologies of feminism have a shared goal of achieving gender equality.

Trans women have a gender identity that does not align with their male sex assignment at birth, while intersex women may have sex characteristics that do not fit typical notions of female biology.