What it is
The H1 is the main heading of a page, the title of the content itself rather than the title on the browser tab. A page should have exactly one. It tells both the reader and the search engine, in plain words, what the page is for: on a product page the H1 is the product name, on a category page it is the category. When a page has none, or carries several competing H1s because a theme wrapped a banner and a logo in the same tag, that single clear signal is gone.
How common it is
Two in three audited stores (67%) get the H1 right. The audit reads product and category pages and flags two faults: a page with no H1 at all, and a page with more than one. Both blur the topic. A missing H1 is common on templated category pages, and multiple H1s show up when a slider or a promotional block carries its own heading tag.
Why it costs you
The H1 is where a page states what it is. With it missing, or split across competing tags, the page no longer declares its topic, and Google infers the subject from scattered cues like body text, menus, and filters. That guesswork makes it harder for Google to connect the page to the search it should answer. A single H1 with the product or category name lets the page say clearly what it is.
Check it in 30 seconds
Open a product page, right-click, choose View Page Source, and search for “<h1”. You want one result, and it should name the product. None, or several, means the page is sending Google a muddy signal about its own topic.
Read next: Ecommerce SEO: Turn Search Visibility Into Revenue
Run the free audit to see which pages are missing a clear main heading.