What is a post format?
A post format is used by a theme for presenting posts in a certain format and style, such as “standard”, “image”, “gallery” “audio”, “video”, “quote”, “status”, “aside”, “link” and/or a “chat” post. You can actually read thorough explanation of post formats on WordPress codex pages. (Post formats should not be confused with post types!)
There is a problem, though
Post formats styling and support is left solely for a theme you are using. And there is no standardized way of displaying post formats. So, this can change from theme to theme:
- one theme can only distinguish post formats simply with an icon,
- the other one goes further by displaying actual format media and/or text automatically, taken from post content,
- another theme may even require setting up a special post custom field to display post format media,
- yet another theme may not support all