Origin

An Origin is the combination of a URL's protocol, domain and port (like https://example.com) that the browser uses as the security boundary between sites.

An Origin is the browser's unit of security boundary: two addresses with a different protocol, domain or port count as “different origins,” even if they belong to one business. This boundary underlies the same-origin policy that decides which other page's data a page can access. For analytics it has two consequences. First, a cross-origin request has its own rules, and without the destination server's explicit permission some information (like a resource's precise timing) stays hidden. Second, from a server-security view, the Origin header in a request says which site the request came from and must be read server-side, not by trusting a client-declared value in a body. The difference between an origin and a domain is exactly this detail: an origin is more precise because it also includes the protocol and port.