Field notesStructured dataTechnical
Structured data worth adding, and the rest
Schema.org has hundreds of types. A handful do most of the work for being understood by machines; the remainder are mostly effort with little return.
AI Detective6 min read
Structured data advice tends toward maximalism: mark up everything, more types is better. In practice a small number of types carry most of the value, several are commonly implemented incorrectly, and some are effort you will not recover.
The types that earn their place
| Type | Use it for | Why it matters |
|---|---|---|
| Organization | Every site, on the homepage | States who the site belongs to. The single highest-value markup for most businesses. |
| Article / BlogPosting | Editorial content | Carries author and dates unambiguously instead of leaving them to be parsed out of prose. |
| Product | Commerce | States price, availability, and identifiers as data rather than as formatted text. |
| LocalBusiness | Businesses with a physical location | Address, hours, and service area, where inconsistency across the web is especially common. |
| BreadcrumbList | Deep site hierarchies | Makes a page's place in the structure explicit. Cheap, usually automatic. |
| FAQPage | Genuine question-and-answer content | Useful when the questions are real. Frequently misused for invented filler. |
For most sites, Organization plus Article covers the majority of the available benefit. Adding those correctly beats adding six types carelessly.
The mistakes that neutralise it
Markup that disagrees with the page
Structured data must describe what is actually on the page. A price in markup that differs from the displayed price, or a rating that appears nowhere visible, is a contradiction — worse than no markup, since disagreement is itself a negative signal and platforms treat it as a guidelines violation.
Injecting it with JavaScript
Markup added by a tag manager is invisible to anything that reads the served HTML without executing scripts. Testing tools that run JavaScript will show it working, which is how this survives undetected. Identity markup in particular belongs in the initial response.
Review and rating markup you should not have
Self-serving aggregate ratings — a business marking up its own five-star average with no verifiable basis — are explicitly against platform guidelines and are the most frequently penalised misuse. If you do not have genuine, verifiable reviews, do not mark up reviews.
Set once, never revisited
Companies rebrand, move, and change what they sell. Structured data is rarely updated alongside, so stale assertions persist — sometimes for years, in machine-readable form, which is the worst place for them to be wrong.
Where the returns stop
Schema.org contains types for almost everything. Beyond the core set, additional markup rarely changes how a page is understood in proportion to the work of adding and maintaining it correctly.
Validating properly
- View source — not inspect — and confirm the markup is in the served HTML.
- Run it through a schema validator to catch syntax and required-property errors.
- Read what it asserts and compare it against the visible page, line by line. This step catches the errors that matter and no tool does it for you.
- Re-check after any rebrand, migration, or template change.