An Aerogram or Air Letter, also called an aérogramme, is a thin lightweight piece of foldable and gummed paper for writing a letter for transit via airmail, in which the letter and envelope are one and the same. Most postal administrations forbid enclosures in these light letters, which are usually sent abroad at a preferential rate.

The majority of aerograms have an imprinted stamp, however, some countries, such as New Zealand, Rhodesia and Ireland, sell unstamped aerograms. The unstamped aerograms are referred to as 'formular aerograms'. They can be issued by either postal authorities or by private companies. Senders are required to write their name and address on the reverse.