Lost and Found on the Plane and in the Terminal

When you leave an Item on the plane usually the Airline will take that item into custody and list it on hand in their baggage tracking system, they will try to identify it the Traditional way, IE name tags, however electronics are a little harder to find the owner off, unless you have an electronic identifier such as a identity screen when the iPad, iPhone is turned on for example. The other way is to check by which seat it was found in and match that to the reservation of that particular flight. Do not leave it too long to contact the Airline after you discover you left something on board as the Airline generally has a policy of sending all unclaimed items to a designated holding station after a certain number of days and subsequently Auctioned off there after.
If you leave an Item in the Airport Terminal then that normally becomes the responsibility of the Department Of Airports and there is where you would inquire.