The short answer
A postcard is a printed card you mail without an envelope, with a picture on one side and room for a message and an address on the other. Nearly every modern card uses a divided back: the message goes on the left, the address on the right, and the stamp sits in the top-right corner. Knowing those parts makes it easier to date old cards, describe what you collect, and know where the pen goes when you send one.
The front: the picture side
The front — also called the picture side — carries the image. Vintage-era cards show everything from downtown streets and grand hotels to national parks and roadside scenes, often with a caption printed along the edge. In the atlas, the front is where every vintage-style design lives: a real place rendered as a card you can send.
The printed frame around the image is sometimes a clue to the era — wide white borders from the 1910s and 1920s, linen-finish cards from the 1930s and 1940s, and glossy chrome cards from the 1950s onward. The how to date a postcard guide walks through the clues in order.
The back: message and address
Before 1907 in the United States, the whole back of a card was reserved for the address, so people squeezed messages onto the front beside the picture. In 1907 the divided back was allowed: a vertical line split the card, with the message on the left and the address on the right. If you see handwriting on the front of an old card, it is often a sign of that earlier mailing style. The full timeline lives in the history of the postcard.
The stamp corner and the postmark
The stamp goes in the top-right corner of the address side, and the postmark — the cancellation stamped over it — is how the postal service marks the card as mailed. Collectors usually leave both in place, because they add history: a readable postmark with a town and a date can tell you where and when a card traveled. The guide to what makes a postcard valuable explains why that matters.
Why the anatomy matters to collectors
Knowing the parts helps you describe a card precisely. Is the front a real-photo view or a printed illustration? Is the back divided or undivided? Those small details separate eras and can change a card's value. If you are new to the hobby, how to start a postcard collection suggests where to begin and what to look for.
The same anatomy in the atlas
Every design in this atlas is a picture side waiting for its back: when you order a card, the message and address sides follow the classic layout, so the card you mail looks and works like the ones collectors have sent for over a century. The standard postcard sizes guide lists the common formats, and the how to send a postcard guide covers the whole ritual from pen to mailbox.
Where does the message go on a postcard?
On a divided-back card, the message goes on the left side of the back and the address on the right. If you are not sure what to say, what to write on a postcard has ready-made ideas.
Can you write on the front of a postcard?
Modern cards leave the front for the picture. The caption is printed there, but your handwriting belongs on the back. On very early cards — before divided backs existed — people did write messages on the front because there was nowhere else.
What is an undivided-back postcard?
An undivided-back card is one printed before the divided back became standard, with the entire back given to the address. These are among the older cards collectors look for; the history guide places them in the timeline.