a <#cover> with an inscription or illustration advertising some product or service of the sender.

a sheet of paper with a strategically placed stamp-like <#indicia=indicium> that prepays <#airmail=air mail>  <#postage>.  After the message and the name and address of the recipient are written, the sheet is folded, sealed and mailed.  No enclosures are permitted.  Also see <#privag=Private Aerogram>.  <#scott=Scott> numbers for aerograms and <#amenv=air mail stamped envelopes> begin with UC.

a machine that affixes <#stamp=stamps> to an envelope, card or <#wrapper>.  The first affixing machines appeared in the 1850s but were not widely used until the early 20th century

see <#aerogram=Aerogram>.

see <#parcelairlift=Parcel Airlift>.