Scientifically, Gender refers to the biological sex of an organism. In common culture, it can be used in a multitude of other ways, however. Possible meanings include, but are not limited to[1]:

Generally, there are only two commonly-identified genders - Male and Female. There are many sub-genders however, such as bigender, agender, pangender, and many more.

The gender of humans is usually determined at birth by a quick examination of the *entials. However, in rare cases, a baby can be born with ambiguous *enitalia[2], or can be born with one set of *enitals, but with the chromosomes of the opposite sex[3].