Postcard
A postcard was a souvenir in the form of a postal letter. Postcards contained images, often photographs of special landmarks or objects with room at the back of the card to write a letter.

In a holographic re-creation of 1944, Brigitte had promised to write a postcard to Bobby Davis, which was prevented by the outbreak of the war. When Bobby encountered Brigitte in Sainte Claire, he told her she owed him a postcard. ()

A rack of postcards was among the items on display at Alexandria Books. ()

While inspecting the prototype  starship  from the outside in 2151, Chief Engineer Tucker jokingly asked Captain Jonathan Archer whether he planned to pose on Enterprises hull for some postcards, when Archer insisted newly installed hull plating match the color of the nacelle housings. ()

When the  prepared to enter a subspace compression anomaly in 2374, Jadzia Dax told Benjamin Sisko she'd send him a postcard, when Sisko expressed sorrow for not going along to explore the anomaly. ()

See also 
 Subspace postcard

External link 
 
Communications technology