Origin server
The server responsible for the requested resource, as distinguished from an intermediary cache or reverse proxy.
REFERENCE / GLOSSARY
Terms worth keeping straight.
Use these definitions when reading traces, debugging a site or writing an operational note.
Representation
A transferable form of resource information, such as HTML, JSON, CSS or SVG.
Method
The action requested from the target resource, such as GET, HEAD or POST.
Validator
Metadata such as ETag or Last-Modified used to determine whether a cached representation remains current.
SNI
Server Name Indication is a TLS extension that lets a client announce the intended hostname during a handshake. It is not an HTTP header and must not be confused with the Host field.
Reverse proxy
A server that receives client requests and forwards them to one or more backend services. Its routing and error handling affect what the client actually sees.