Deltiology is the study and collection of postcards. It initially took 20 years for the name to appear in a dictionary. Compared to philately, the identification of a postcard's place and time of production are rather decentralised and unregulated. Some collectors choose to limit their acquisitions to cards by specific artists and publishers. Picture postcards (PPC) can be assigned to ''the Golden Age of Postcards" (1898-1919), the time of the linens (1930-1950), or to the modern chromes (after 1940, color photography).

Postcards are collected by historical societies, libraries and genealogical societies. One of the most popular areas of collecting is ''town views''. Most collectors start by collecting views of the town where they reside or the town where they grew up. With many small towns having hundreds of different cards available, it is the area that keeps a collector busy for years.

Worldwide, deltiology is the third largest collecting hobby after stamp collecting and coin/banknote collecting. Professor Randall Rhoades of Ashland, Ohio, coined this word ''deltiology'' in 1945.

More Info: en.wikipedia.org