Headings are an outline
Take any well-organized document and strip away the paragraphs. What remains, the headings in order, should read like a table of contents. That is the idea behind heading tags in HTML. They are labeled levels, from H1 (the most important) down to H6, that describe how a page is organized. Most pages only need the first three.
Readers use headings to decide where to look. Many visitors skim before they commit to reading, and a page that offers clear signposts is easier to trust and navigate. Screen reader users also often jump from heading to heading to understand a page and find the part they need. Search engines read headings too, as a hint about what each section covers, though how much weight they give is not publicly known and should not be your main concern. Write for the reader and the rest tends to follow.
What each level is for
H1 is the main heading and says what the whole page is about. In most systems it is generated from the page title. A page normally has one clear H1. Plenty of sites technically work with more than one, but a single H1 keeps the outline simple and is the easiest convention to follow.
H2 headings divide the page into its major sections. If a page were a short book, these would be the chapters. A typical article has anywhere from three to eight.
H3 headings divide an H2 section into smaller parts, for example three options under a heading about choices. Use them when a section is long enough to need breaking up. A page does not need H3 headings at all if the sections are short.
H4 to H6 exist, but if you need them often the page may be trying to do too much and could be split.
A simple example
Suppose a page about choosing a watering schedule for houseplants. A clean outline could look like this:
- H1: How to Water Houseplants
- H2: Signs of too much water
- H2: Signs of too little water
- H2: Setting a schedule
- H3: Small pots
- H3: Large pots
- H2: Seasonal changes
Anyone reading only that list knows what the page covers, and can jump straight to the part they care about. That is the test: if the headings alone give a sensible summary, the structure is working.
Common mistakes
Skipping levels. Going from H2 straight to H4 breaks the outline for people using assistive tools, who expect sections to nest in order. Move down one level at a time.
Using headings for style. If you want larger or bolder text, use styling instead. Marking up a pull quote, a button label or a sidebar title as a heading adds clutter to the outline. The reverse is also true: do not fake headings with bold paragraphs, since they will not appear as headings to anyone using the structure.
Vague headings. “More information” and “Overview” tell nobody anything. A heading should say something about the section under it.
Keyword repetition. Putting the same phrase in every heading looks unnatural and reads badly. This is one of the patterns discussed under keyword stuffing. Use natural wording, with a related phrase where it fits.
Headings that are too long. A heading should be scannable at a glance, usually a short phrase rather than a full sentence.
Theme or template quirks. Some themes mark up the site name, sidebar widgets or footer headings as H1 or H2. Check the actual page source or use a browser extension that shows the outline, because what looks right on screen can be wrong in the code.
Headings and the rest of the page
The heading and the title tag do different jobs. The title tag is the label used in tabs and results; the H1 is the visible headline. They usually say the same thing in slightly different words, and they should agree on the topic. A page whose title says one thing and whose H1 says another leaves both readers and search engines unsure.
Headings also work best when the content under them answers what the heading promises. If a heading asks a question, the next paragraph should answer it plainly. If you are writing to meet a particular search intent, headings are a good place to confirm you have covered the sub-questions that go with it.
Checking your own pages
A quick review takes only a few steps:
- Open the page and list its headings in order, using a browser tool or the source.
- Confirm there is one H1 and that it matches the page topic.
- Check that levels never skip.
- Read the list aloud. Does it summarize the page?
- Remove or rewrite headings that are vague, decorative or repetitive.
Fixes are usually small and cheap, and they improve the page for everyone who reads it, however it is read. No heading change can promise a ranking improvement, but a clearer outline almost always makes a page easier to use.