Or picture post-cards, as they used to be called. The hobby has existed for over a hundred years, and according to Wikipedia, it's the third largest collecting hobby after philately and numismatics.[citation needed] However, the term itself wasn't coined until the late 1940s, from the Greek root deltíon, diminutive of déltos, writing tablet.
I'm not a formal deltiologist, but I do pick up a couple postcards when I'm touristing because the professional pictures are always better than mine.
---L.
