Gender refers to the psychological sense of maleness or femaleness related to one's culture or society, whereas sex refers to biological attributes. Gender development involves learning gender roles and stereotypes from a young age through socialization. Gender identity forms between ages 2-3 and involves identifying as male or female, while gender constancy develops at ages 6-7 with the understanding that gender is permanent. Gender stereotyping can be positive or negative, but is inherently harmful as it reduces individuals to narrow roles and leads to making assumptions about people based on their gender.