A few things to check for:
Non-breaking text in the title, content, and comments should have no adverse effects on layout or functionality. Check the browser window / tab title. If you are a plugin or widget developer, check that this text does not break anything.
The following CSS properties will help you support non-breaking text.
Putting special characters in the title should have no adverse effect on the layout or functionality.
The post title renders the word “with” in italics and the word “markup” in bold. The post title markup should be removed from the browser window / tab.
This post has no title, but it still must link to the single post view somehow.
This is typically done by placing the permalink on the post date.
This post has many categories.
Category: Alignment, Aside, Audio, Captions, Chat, Child Category 01, Child Category 02, Child Category 03, Child Category 04, Child Category 05, Codex, Comments, Content, Corner Case, Embeds, Excerpt, Featured Images, Formatting, Gallery, Grandchild Category, Images, Jetpack, Link, Lists, Markup, More Tag, Parent Category, Password, Pingbacks, Post Formats, Quote, Shortcodes, Standard, Status, Titles, Trackbacks, Twitter, Uncategorized, Unpublished, Video, VideoPress Comments: Comments Off on Many Categories