What is Structured data?
Also known as: Schema markup, JSON-LD
Structured data is machine-readable markup added to a page that tells search engines what the content means — that a number is a price, or that a page describes a product.
For ecommerce the most valuable type is Product markup, carrying price and availability. It is what makes a result eligible to display those details directly in search.
Eligibility is not a guarantee of display, and markup must describe what is genuinely on the page. Marking up prices or ratings that do not exist is a policy violation that can remove rich results entirely.