Note that while the actual post content entry won’t change, the theme can use this user choice to display the post differently based on the format chosen. For example, a theme could leave off the display of the title for a “Status” post. How things are displayed is entirely up to the theme, but here are some general guidelines.
aside – Typically styled without a title. Similar to a Facebook note update.
gallery – A gallery of images. Post will likely contain a gallery shortcode and will have image attachments.
link – A link to another site. Themes may wish to use the first tag in the post content as the external link for that post. An alternative approach could be if the post consists only of a URL, then that will be the URL and the title (post_title) will be the name attached to the anchor for it.
image – A single image. The first tag in the post could be considered the image. Alternatively, if the post consists only of a URL, that will be the image URL and the title of the post (post_title) will be the title attribute for the image.
quote – A quotation. Probably will contain a blockquote holding the quote content. Alternatively, the quote may be just the content, with the source/author being the title.
status – A short status update, similar to a Twitter status update.
video – A single video. The first tag or object/embed in the post content could be considered the video. Alternatively, if the post consists only of a URL, that will be the video URL. May also contain the video as an attachment to the post, if video support is enabled on the blog (like via a plugin).
audio – An audio file. Could be used for Podcasting.
chat – A chat transcript, like so:
John: foo
Mary: bar
John: foo 2
Note: When writing or editing a Post, Standard is used to designate that no Post Format is specified. Also if a format is specified that is invalid then standard (no format) will be used.