Shawrma originated in Eastern Mediterranean part of the world it aslo now exist in turkey as well as Arabian countries.
It is basically Meat or chicken placed on a spit which is the thing in the image below
It is grilled through out the whole day...as the chief slice a piece of it he turns it so the uncooked part faces the heat and be cooked.
Shawarma can be served on a plate , or as a sandwich or wrap.
but usually it isn't eaten alone...it has other accompaniments such as tabbouleh, fattoush and served with a special sauce CALLED "Tomiaa"
If you ever visited an Arabian country or went to Turkey don't forget to try it.
although it has spread all around the globe now ...you'll find it in your country :D