Sex is a medical term used for the classification of people as "male" and "female", usually as a birth assignment based on the appearance of an infant's external genitalia. However, sex is more complicated than that. A person's sex is a combination of bodily characteristics including: chromosomes, hormones, internal and external reproductive organs, and secondary sex characteristics that develop during puberty. The common division of sex into strictly "male" and "female" ignores natural sexual variations that do not easily fit into one of the two categories, such as various intersex traits. Problematic and medically inaccurate language for sex includes phrases like "biologically [fe]male", "genetically [fe]male", or "born a [wo]man]". Such phrases over-simplify the complexities of people's biology and regard birth assignments as more important than gender identity.