What Is Structured Data and Why Does Your Site Need It?
When a search engine bot crawls your page, what it encounters is plain text and HTML tags; it has to guess whether a heading really is the page title, whether a date is the publication date, whether a name is the author. Structured data removes that guesswork and makes the information on your page machine-readable according to the Schema.org vocabulary. The search engine now receives facts like "this is an article headline", "this is a product price", "this is a frequently asked question" directly, with no interpretation required.
That clarity helps the search engine classify your page correctly, especially on sites with a wide variety of content types (blogs, e-commerce, service pages). Adding structured data is not compulsory, but applied correctly it gives you an extra measure of control over how your page is represented in search results.
The Difference Between JSON-LD, Microdata and RDFa
There are three ways to mark up Schema.org data: JSON-LD, Microdata and RDFa. The format Google recommends is JSON-LD; it is added as a self-contained <script type="application/ld+json"> block inside <head>, without touching the visible HTML of your page. Microdata and RDFa are still supported, but those formats require attributes to be embedded directly inside your HTML tags, which makes them harder to maintain when the template changes or the content is updated.
In practice JSON-LD's biggest advantage is that it is separable: you can add or remove a single block of code with no risk of breaking the existing page design. That makes it the more practical choice for most projects, in terms of both development and maintenance.
Rich Results Are Not a Guarantee
Adding valid structured data can make your page eligible for rich results in Google Search: FAQ content may appear as an expandable list, product pages may be listed with price and availability. There is no guarantee of any of it, however. Google decides which result is shown when, and in what format, through its own algorithm; adding structured data may improve visibility, but it does not directly raise rankings.
Which Schema Type Should You Use, and When?
There is an appropriate Schema.org type for every kind of page. The four types below cover the most common needs:
| Schema type | When to use it | Core fields |
|---|---|---|
| Article | Content pages such as blog posts, news items and guides | <code>headline</code>, <code>author</code>, <code>datePublished</code>, <code>image</code> |
| Product | Product pages showing a price and availability | <code>name</code>, <code>description</code>, <code>image</code>, <code>offers</code> (price, currency, availability) |
| FAQPage | Question-and-answer blocks that genuinely appear on the page | <code>Question</code> / <code>acceptedAnswer</code> pairs inside <code>mainEntity</code> |
| LocalBusiness | Business or branch pages with a physical address | <code>name</code>, <code>address</code>, <code>telephone</code>, <code>url</code> |
In the Product schema, availability is expressed with one of the values InStock, OutOfStock or PreOrder; that value has to match exactly the stock information you actually display on the page. In the LocalBusiness schema, the address is structured under the PostalAddress type with street, city, postal code and country fields.
The Golden Rule: Mark Up Only Information That Genuinely Appears on the Page
Google's official structured data guidelines are clear: marking up content that is not present on the page is prohibited. Structured data exists to explain information the user can genuinely see in the browser more clearly to the search engine; it is not there to present information that is absent from the page as though it were there.
This principle explains why the KEYDAL JSON-LD Generator deliberately offers no star rating or review count schema. Invented scores and fake review counts are among the spam patterns Google detects most often and punishes most severely; trying to show a star rating in search results that does not genuinely exist on the page can earn your site a manual action, and getting such a penalty lifted takes time. That is why this tool produces only schema types grounded in real, verifiable page content, such as Article, Product, FAQPage and LocalBusiness.
Common Mistakes
- Adding information to the schema that does not appear on the page: writing a price that is not displayed, or a question that is not on the page, into the FAQPage schema.
- Adding several contradictory schemas to the same page: marking one page as both Article and Product makes it harder for the search engine to classify it correctly.
- Forgetting to update the JSON-LD when the content changes: the
availabilityfield still reportingInStockafter the product has sold out, for example. - Leaving required fields out: without fields such as
headlinefor Article oroffersfor Product, the schema may not be considered valid. - Writing the FAQPage question-and-answer text differently from the actual visible text on the page; the marked-up question and answer must be readable there word for word.
Always Validate Before You Publish
Writing a field incorrectly or skipping a required one can stop the page from being considered for a rich result at all. Even if the code looks syntactically valid, the schema may still go unused if one of the required fields Google expects is missing.
Validation is not a one-off task. When you update the page content (a price changes, a new question is added, the author changes), you have to update the structured data at the same time. Otherwise the information visible on the page and the information marked up in the schema drift apart; that misleads both the user and the search engine, and gets flagged as an error again the next time you validate.
A Quick Start With the KEYDAL JSON-LD Generator
Writing the right fields in JSON format by hand is error-prone; a forgotten comma or a mismatched quotation mark produces invalid JSON-LD. The KEYDAL JSON-LD Generator converts the information you enter into form fields into valid JSON-LD output automatically for the Article, Product, FAQPage and LocalBusiness schemas; all you have to do is copy the output and paste it straight into the <head> section of your page.
After using the tool, do not forget to run the output through the Rich Results Test for one final check before publishing — and keep in mind that you need to keep your structured data current as your page content changes.