A bird must conform to the breed standard. Cocks, cockerels, hens and pullets can all be shown.
Each breed belongs to a class of birds. Such as, the Mediterranean, American, Asiatic, etc. classes for largefowl. Bantams have different types of classifications. Such as, RCCL (Rose combed clean-legged), SCCL (single-combed clean-legged), Feather-Legged, etc.
Within the breeds, there are varieties of birds. The varieties describe the colors and types of birds. For example:
A Leghorn belongs to the Mediterranean class.
A particular Leghorn can be white with a single comb or someone may be showing a dark brown Leghorn that has a rosecomb. These birds will compete against each other for the class.
The winner of the class will compete with other winners of the other respective classes and will proceed to the Champion Row where the winner and reserve of the show will be chosen.
These is just a general run-down.
PLEASE, do not go before the show starts. People are cranky from lack of sleep, are busy getting their birds prepped for the show and do not want to talk. During the judging is a good time to go to the sale area and check out some birds. Ask people around that area that look like they know what they are doing.
Usually 11AM is a good idea to start finding people.