This page is a vocabulary of some terms I use, I'll add as I go along. These are what these terms mean to me, so if I have a misconception about anything please feel free to let me know.
Artist Signed (A/S) - a printed or facsimile version of an artists' signature. On postcards the signature is actually part of the photograph.
Autograph - a physcial signature, something actually signed by the person
Cabinet Photo - a photo style popular from the 1860s - late 1890s (about 4.5 x 6 inches)
CDV - Carte de viste, a small photo style popular from the 1850s - 1880s. (about 2.5 x 4 inches)
Divided Back postcard - A postcard which has space allocated for a message and an adress on the back side. Divided back postcards began in 1907 (in the USA), a few years earlier in Europe.
Early 20th Century Postcards - Postcards created before 1918 or so. Most USA cards from this era were printed overseas, usually in Germany.
Linen Postcards - Postcards created from ragstock, popular from around 1932 to 1952. Cards have a rough texture & colors are bright & a little garish.
RPPC - Real Photo Postcard. These are photos printed with a postcard backing. Some are mass produced, many were part of a formal portrait package offered by a photographer, and some are just snapshots people took with very inexpensive cameras. There have been RPPCs since the early 20th century to present day.
Snapshot - This is an informally posed or candid photo usually taken by an amateur photographer with an inexpensive camera. Snapshots date from the early 20th century on.
Standard/Chrome Postcards - Postcards which are 3.5 x 5.5 inches in size, printed from Kodachrome or Ektachrome images. Most date from the early 1950s to the early 1980s, though some date from as early as 1939 or so. You can see dots or lines under magnification.
Undivided Back Postcard - Postcards created before 1907 (in the USA). It was only legal to write the address on back.
White Border postcards - created from 1918-1932, cards had a white border in order to save ink. The quality of the color and printing was generally poorer than earlier cards.