In one sentence
Schema.org is a "vocabulary list" that correctly tells machines (AI / search engines) things like "this page is an article," "this is company information," "this is a FAQ." It was jointly created by Google, Microsoft, and Yahoo.
What does this look like in practice?
For example, suppose your site has an article titled "How to get from Tokyo Station to Haneda Airport." With plain HTML, AI sees nothing but "a blob of text."
If you use the Schema.org Article schema, you can write:
{
"@type": "Article",
"headline": "How to get from Tokyo Station to Haneda Airport",
"author": "XX Editorial Team",
"datePublished": "2026-05-24"
}