Orc is the anglicised version of the Sindarin
word yrch, the servants of the Ainur Melkor
. They were most likely created by the perversion of Elves
being unable to create
anything of his own. As such, they shared the immortality of the Elves
, but not their appearance. Black, sallow, and stunted, most preferred darkness, however breeds such as the Uruk-Hai were able to endure sunlight.
Tolkien referred to the Orcs as Goblins
in The Hobbit
, but they're the same thing.