Sex refers to the biological distinction between females and males, primarily based on differences in their reproductive organs, chromosomes, hormones, and other physical characteristics that are typically assigned at birth. It is generally considered a binary classification in many societies, although biological variations and intersex conditions exist that do not fit neatly into this binary. Sex is often conflated with gender, which is a social construct referring to the roles, behaviours, identities, and expectations that a society ascribes to individuals based on their perceived sex. While sex is rooted in biology, gender is culturally defined and can vary widely across different societies and time periods.