The orc were once elves but Sauron corrupted them and mutated them into the orc. The orc do not like to be in sunlight, that is why you see many orcs in caves or mines such as Moria for example. Orcs are not all united under one banner. They are scattered and divided into clans that war against one another. Though Orcs fight
along side and obey Uruk-Hai they despise them and the feeling is mutal on the other side as well. Orcs are short in stacher and are dark and ugly in appearence.