What Is Structured Data?

Labels for a machine

A page shows "₹999" and a human knows it's the price. A machine sees a string. Structured data is a block of labelled facts added to the page, this is a Product, this is its price, this is its currency, so nothing has to be inferred.

The vocabulary is schema.org, shared across search engines. The usual format is JSON-LD: a script tag holding JSON, kept separate from your markup, which is why it's the recommended option, you can change your layout without touching it.

article-jsonld.html

<script type="application/ld+json">{  "@context": "https://schema.org",  "@type": "Article",  "headline": "What Is an API?",  "description": "An API is a defined way for one program to ask another for something.",  "datePublished": "2026-06-01",  "dateModified": "2026-08-01",  "author": {    "@type": "Person",    "name": "Daksh Bathla",    "url": "https://navitallabs.com/learning/instructors/daksh"  },  "publisher": {    "@type": "Organization",    "name": "Navital Labs",    "url": "https://navitallabs.com"  }}</script>

The types most sites need

Start here, ignore the rest

Type	Use on	What it can produce
Organization	Homepage	Knowledge panel details, logo
WebSite	Homepage	Sitelinks search box
Article	Blog posts, lessons, guides	Author and date shown in results
BreadcrumbList	Any nested page	The path shown instead of a bare URL
Product / Offer	Product pages	Price and availability in results
FAQPage	Pages with real Q&A	Expandable questions in results
Person	Author and team pages	Author attribution
DefinedTerm	Glossary entries	Term and definition understood as such

schema.org has hundreds of types. Almost nobody needs more than the eight above, and adding obscure types has no observed benefit, the value is in the ones search engines actually consume.

The one rule

Every fact in the markup should be findable by a reader on that page
Dates in the markup must match the dates shown
The author named must be the actual author, with a real page
No aggregate ratings without real, visible reviews
Update the markup when the page changes, stale structured data is wrong structured data

Generating it from your data

Hand-writing JSON-LD per page guarantees drift: the page changes, the markup doesn't. Generate it from the same source the page renders from, and the two can't disagree.

schema.ts

export function articleSchema(lesson: Lesson, author: Instructor) {  return {    "@context": "https://schema.org",    "@type": "Article",    headline: lesson.title,    description: lesson.description,    datePublished: lesson.publishedAt,    dateModified: lesson.updatedAt,    author: {      "@type": "Person",      name: author.name,      url: `https://navitallabs.com/learning/instructors/${author.slug}`,    },  };}

One function, one source of truth, and the markup is correct by construction rather than by someone remembering.

Validating before shipping

Run the page through a rich results testSearch engines publish free validators that report errors and warnings against a live URL or pasted HTML.
Fix errors; read warnings and decideErrors block the feature. Warnings are usually optional fields worth adding if you genuinely have the data.
Re-check after a template changeThis is where drift enters, a layout edit that removes a visible date leaves the markup claiming one.

Expect nothing dramatic. Structured data doesn't raise rankings by itself; it makes your result more informative and makes your page easier to understand and cite. Both are worth having, and neither is a shortcut.

Common mistakes

Marking up facts that aren't on the page
Fake review or rating markup, which risks rich results site-wide
Hand-writing JSON-LD per page, guaranteeing it goes stale
Adding a dozen obscure types nothing consumes
Expecting a ranking increase rather than a better-presented result

Key takeaways

Structured data labels page facts for machines, using schema.org, usually as JSON-LD
Eight types cover almost every site
It must describe what a reader can see, that rule is enforced
Generate it from the same data the page renders, then validate

Try it yourself

Run one of your pages through a rich results test. If nothing is detected, add Article or Organization markup generated from data you already have, and re-test. That single addition is usually the largest structured-data gap on a small site.

CHECK YOUR UNDERSTANDING

1. What does the lesson say happens if you mark up reviews or prices you don't actually show on the page?

2. Why does the lesson recommend generating JSON-LD from the same data the page renders, rather than hand-writing it per page?

3. What outcome should you realistically expect from adding correct structured data, per the lesson?

4. The lesson lists eight schema.org types most sites need. What's its stance on going beyond those?

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