What it is
People can look at a page and tell a price from a phone number. A machine cannot, unless you label things. Structured data is that labeling. You tag the parts of a page using a shared vocabulary, almost always schema.org, written in a small block of JSON-LD. The result is a clean, explicit description of what your content means, sitting alongside what it says.
Why it matters
This is how you speak to the search engines and AI systems audiences directly. Structured data powers rich results in Google, feeds knowledge graphs, and gives AI models a reliable read on your entities and facts instead of an inference they might get wrong. When a model has to choose a source to cite, the one it can parse cleanly has an edge over the one it has to interpret.
What to do
Add schema markup for your most important page types first: FAQ, how-to, product, article, and organization. Use JSON-LD, validate it with Google's Rich Results Test, and keep it in sync with the visible content so the labels never contradict the page. Run WAIO Engine to see which pages are missing structured data.