What Is Schema Markup?

Schema markup is a small block of machine-readable data on a page that says what the page is. Not how it looks — what it is: a local business with these hours, an article by this author, a question with this answer. Search engines read it, AI systems read it, and it costs nothing to add.

What it is for

A page about emergency plumbing in a particular town looks, to software, like a lot of words. Schema markup adds an unambiguous statement alongside it: this is a service, offered by this business, in this area, with these hours and this phone number. The vocabulary comes from Schema.org, which is a joint effort by the search engines, and the encoding is usually JSON-LD.

The benefit is not mystical. It removes ambiguity, and systems that have to choose which of ten businesses to name in an answer prefer the ones they are not guessing about.

What to mark up, in order

Your business, on every page: name, address, phone, hours, area served. Your services, on the pages that describe them. Your questions and answers, on pages that actually show them to a reader. Your articles, with a real author and a real date.

Google publishes what it supports and how, and the list of supported types is shorter than the vocabulary, so start there rather than marking up everything schema.org allows.

The rule people break

Structured data must describe what the page shows. Marking up an FAQ that is not on the page, or reviews that are not displayed, is against Google’s guidelines and gets pages penalised rather than promoted. This site’s own pages are built that way deliberately: the questions in the markup are read off the page, so the two cannot drift apart.

The bottom line

Add the basics, make sure they match what a reader sees, and move on. Schema markup is table stakes rather than a lever — but a page a machine has to guess about is a page that loses to one it does not.