Headings
Headings are vitally important when assessing document structure as well as scanning and navigating a webpage (see LevelAccess's simulation of Web Headings for Screen Readers). They also help with search engine optimization (SEO), letting search engines know what topics your webpage contains.
Headings do not stand alone. They introduce subject matter. Headings should not be used to make paragraphs stand out, as that makes the content unscannable by your constituents. They should be no longer than 140 characters.
Proper Semantic Usage
In general:
- Document Title: A level 1 heading (sometimes called "topic" or "heading") should be available somewhere at the top of your document. It typically defines the page's primary topic. It is often similar to the document or page's title.
- Headings and Subheadings: A level 2 heading (sometimes called "subtopic" or "subheading") must come after the level 1 heading. You can have multiple level 2 headings as long as each one appropriately introduces a topic.
- Level Order: Level 3 through 6 headings come after the previous levels ordered numerically. Again, you can have multiple headings of these different levels, but they must be relevant and ordered numerically. Do not skip a heading level. Do not go out of order.