What is Schema Markup?

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Schema markup is the specific vocabulary used to add structured data to a web page — a shared library of tags, defined at Schema.org, that label content in a way search engines and AI systems recognize. If structured data is the concept of making content machine-readable, schema markup is the actual vocabulary you implement to do it.

Schema.org defines hundreds of types and properties for describing things — a Product, an Organization, an Article, a Person, an Event — each with its own set of attributes. Marking up a product, for example, means declaring it as a Product with properties like name, sku, brand, gtin, an Offer (price, availability), and an AggregateRating. Search engines read these declarations to understand the page precisely rather than inferring meaning from raw text.

Schema markup is added in one of a few formats, with one clearly preferred today:

• JSON-LD — a script block in the page’s code; Google’s recommended format and the easiest to maintain
• Microdata — attributes added inline to existing HTML tags
• RDFa — an older attribute-based format, less common now

The most valuable ecommerce schema types are Product, Offer, and AggregateRating on product pages, BreadcrumbList site-wide, and FAQPage for genuine Q&A. On Magento (Adobe Commerce), the default markup is often incomplete — missing GTIN, MPN, brand, or ratings — so a common optimization is extending it with complete, valid schema. Correct implementation unlocks rich results in Google and, increasingly, accurate citation by AI Overviews and assistants, which lean on these identifiers to reference products reliably.