Yeee =s render well u basically let see, if i split the character jacket from his body, that jacket would be called a render , and the picture is transparent as well
They usually in png formate
Check this section::
http://forum.nihonomaru.com/anime-renders-37/
look at any of these pictures posted there using elfien lied skin or zeromox skin, u will see no white backrgound right ? that is render, Hope it helps :0)