Advertising: Postcard that was sent by a salesman, or merchant, extolling the benefits of their product, and to entice the potential customer.

Album Marks: Indentations on the corners of cards from weight, or discoloration from leeching of color in album pages.

Artist Signed: A postcard that includes a printed signature (not autograph) of the artist.

Chrome: Cards manufactured after 1939 with a shiny surface (not photo). The term comes from "Kodachrome."

Continental: Any card larger than the modern 4 x 6 size. 3½ x 5½ is the size of most older postcards.

Deltiology: The study of postcards.

Divided Back: Postcards with separate sides for address (right side) and message ( left side). Divided backs appeared as early as 1902 in some foreign countries and in 1907 in the US. This helps to date unused postcards. All cards before these dates have undivided backs.

Embossed: Postcards that have designs pressed into or raised above the card's surface. Heavily embossed postcards have almost a papier-mâché style, which stands greatly above the surface.

Foxing: Brown spots, more commonly referred to as aging, in the paper's surface.

Gelatin: A card with a varnish-like coating producing a glossy surface. The surface usually cracks with age.

Golden Age of Postcards: From 1898 to 1918.

Hold to Light: An HTL is a postcard that creates a lighted or different image if held to the light. There are die cut hold to lights which when you hold them up to the light, usually look like someone has turned on the lights, and transparencies which actually show a picture where, before holding to light, there was only a blank space.

Installment: A series of postcards designed to be sent in sequence, at different times. The completed set when placed top to bottom, or beginning to end, forms a picture.

Linen: Postcards published mainly in the late 20s through 40s, using textured paper with a cross hatched surface resembling linen fabric.

Mechanical: Postcards with moving parts, such as pull tabs or wheels that move.

Novelty: These cards include mechanicals and cards that have item attached, such as feathers, metal medallions, or a packet of seeds, etc. These cards can also be called "Attachments."

Oilette: A term used by Raphael Tuck and Sons of England to refer to a particular style of postcard production. The oilettes often looked like oil paintings, with noticeable brush strokes.

Pioneers: Postcards issued before the Act of Congress in 1898. They carry instructions on the back, such as, "Write the address only on this side - the message on the other," or "Nothing but address can be placed on this side," or "This side for address only."

Private: Postcards produced, not by the government, but by private business or publishers, and bear the words "Private Mailing Card."

Real Photo: An actual photograph printed on photograph paper with a preprinted postcard back. Real photo cards are more desirable than commercially printed postcards. Most real photos are one of a kind, while commercially printed photographs were produced in large quantities.

Series: Groups of postcards that belong together in a collection. The individual cards may or may not have been printed at the same time. More than just a common topic, a series has a common artist or publisher, and is usually numbered.

Sets: Postcards published in a group of two or more. These were sold in packets or individually. Examples include "Days of the Week" or "Months of the Year."

Silk: Postcards where silk fabric is applied to the design, or the whole design is printed on silk fabric, then attached to a postcard back.

Tradecards: Advertising cards issued before 1900. Storekeepers gave then away in products or with the purchase of a product. Most of these have artwork or printing on both sides, and are often the same size as postcards. These are different from an advertising postcard, which was meant to be mailed.

Transparency: A type of Hold to Light postcard that creates its transformation with many thin layers of paper. A change in image is caused by strong light behind the postcard. There are no die cut holes in the surface to achieve this transformation.

Undivided Back: A postcard without a dividing line on the back to separate message from address.