Female, Intersex, Male

The terms "male" and "female" are useful in the field of biology, and describe reproductive systems that play two distinct roles. Male sperm, female egg and female uterus are essential for human reproduction.

It is also true that biologically most people fall into one or the other of these categories.

It is also true that there have always been people who do not neatly fit into either category.

The complicated steps that take a fertilized egg into fetal development, birth, childhood, puberty, and finally into adulthood, afford plenty of opportunity for variation. It's more accurate to think of each distinct aspect of our biological sex--chromosomes, genitals, reproductive organs, hormonal systems, secondary sex characteristics--as individual aspects that exist on a Female<->Intersex<->Male spectrum.

This is very different from the term hermaphrodite, which means an organism that has both a functional male and a functional female reproductive system. Most snail species are hermaphrodites, for example. This can never happen in a human, there are no human hermaphrodites. A person can have a blend of different aspects of bio sex, but not a complete set of each system.