What structured data does and does not do
Structured data describes your page in a format machines read without guessing: this is a product, this is its price, this is whether it is in stock. It is not a ranking factor — Google has been consistent about that — and adding it does not lift a page.
What it does is make you eligible for rich results: the star ratings, prices, breadcrumb trails and event dates that appear under some results and not others. Those change how much of the page a result occupies and how many people click it, which is worth real traffic at the same position.
Eligible is the operative word. Google decides per query whether to show a rich result, and valid markup earns you a place in the draw rather than the prize. A page with perfect Product markup may show a plain result for months.
The types Google quietly withdrew
In August 2023 Google restricted FAQ rich results to well-known government and health sites. In September 2023 it removed How-To rich results entirely. Both changes were announced and both are still ignored by most schema generators, which cheerfully offer FAQ markup as a way to take up more space in results.
The markup is still valid schema.org and still helps machines understand a page. What it will not do — on an ordinary business site — is draw the accordion of questions under your result, which is the only reason most people add it.
This tool labels each type with what Google does today, before you fill anything in. Knowing a rich result is gone is worth more than a generator that produces flawless markup for a feature that no longer exists.
Getting it right, and staying out of trouble
The most common silent failure is a relative URL. Structured data is read outside the context of your page, so /images/logo.png cannot be resolved to anything — Google discards the property, and often the block. Every URL must be absolute, and that is checked here.
The second is invalid JSON. A trailing comma makes the whole block unparseable and Google discards it entirely, with no warning anywhere except the Rich Results Test. Output here is generated rather than hand-typed, which removes that class of error.
The rule that carries actual risk: markup must describe what is genuinely on the page. Review stars for reviews that do not exist, or an FAQ block for questions no visitor can see, is a documented cause of manual actions — Google checks the markup against the page. Structured data is a description, not a claim.