What it is
A web page is written for people, but search engines have to work out what it means. Structured data is a way to state certain facts about a page directly, in a format that software can read without guessing. It is extra information added to the page’s code. Visitors do not see it as such.
A recipe page, for example, can include markup that says “this is a recipe,” along with its name, ingredients, cooking time and a picture. An event page can say when and where the event happens. A business page can state its name, address and opening hours. The markup does not replace the visible text; it labels it.
The common formats
You may come across a few names. The most widely recommended format is JSON-LD, a block of data placed in the page that sits separately from the visible content, which makes it easy to add and maintain. Older formats that mark up the visible HTML directly also exist and still work. They all rely on a shared vocabulary of types and properties, such as “Article,” “Product,” “Organization” and “Event,” which is maintained publicly so that different search engines can understand the same terms.
You do not need to learn the code to benefit. Many content systems and plugins create the markup automatically. Still, it helps to understand what they produce.
What it can and cannot do
Structured data can help search engines understand your content, and for some types it can make a page eligible for richer displays in results, such as star ratings, product details, event information or expandable question lists. Which kinds of rich displays exist, and which sites qualify, changes over time and varies by search engine.
Equally important is what it does not do:
- It is not a ranking switch. Adding it does not promise a higher position.
- It does not guarantee a rich display. Eligibility is not the same as being chosen.
- It cannot make up for weak content.
- It must not describe things that are not on the page. Marking up reviews that do not exist, or information that visitors cannot see, risks the markup being ignored, and in serious cases being penalized.
Common types worth knowing
- Organization or local business: the name, logo, contact details and address of the site’s owner. Useful for local seo and for consistent business details.
- Article or blog posting: the headline, author, publication date and image of a written piece.
- Product and offer: name, image, price, availability. For online stores, accurate product pages and review markup need extra care, because the values must match the page.
- Breadcrumbs: the path from the home page to the current page, which mirrors your breadcrumb navigation.
- FAQ and how-to: questions with answers or steps. Search engines have changed how they show these in the past, so check current guidance before investing effort.
- Event, recipe, video, job posting: useful if your site actually publishes that content.
Choose only types that truthfully describe the page. One page can carry several types if each applies.
How to add it sensibly
- Decide what the page is and which type fits.
- Check whether your platform already produces the markup. Adding a second copy by hand can cause duplicates or conflicts.
- Fill in the required properties for the chosen type, and add recommended ones where you have accurate information.
- Make sure each value matches the visible page: the same price, the same date, the same name.
- Keep it up to date. When a price or event time changes, the markup must change too.
How to check that it is valid
Validation is where most of the practical work lies. Two kinds of check exist.
Syntax and completeness. Free testing tools from search engines and standards bodies let you paste a URL or code and see whether the markup parses, which types were found, and which required or recommended fields are missing. Errors usually mean the markup will not be used. Warnings usually mean optional fields are absent.
Match with the visible page. No tool fully checks this, so read the page and the markup side by side. Does the rating shown in the markup reflect real reviews on the page? Does the price match? Is the author genuine?
Search performance reports can also list the markup types a site has and flag errors across many pages at once. For a small site, checking the home page, a main article and any key templates is a good start, because an error in a template repeats on every page that uses it.
Common mistakes
- Markup that does not match visible content.
- Missing required fields, so the markup is ignored.
- Duplicate markup from both a plugin and a theme.
- Leftover markup from a previous design describing pages that no longer exist.
- Treating markup as a substitute for clear headings and copy.
Where it fits
Structured data is a refinement. First make sure the page is clear: a descriptive title, readable copy and a sensible heading structure. Then add markup that describes what is already there. If it is correct, it does no harm and may help in ways that vary by search engine and over time.