airdrop in now a built in feature of ios. (assuming you are 7.0..or better) that allows you to send some material from one ios device to another, without using e mail or syncing. Pictures, contacts, documents spreadsheets etc.
You find it buy swiping up from the bottom of the creen to see the control center. you can leave it on or off, up to you.
from the app with the document or picture, if you select the output icon, usually a box with an up arrow - one of the choices will be airdrop.
there needs to be somebody to drop it to near you.
If they are dropping to you, and it is turned on, you will get a little notice on your screen that something is coming, and you can decline or accept it.
remember this is a very short range deal, you pretty much need to be next to each other for this to work. But for sharing pictures it is a whole lot more convenient than send an email with an attachment.