AI engineering glossary · Web APIs HTTP
What is ETag?
ETag (also called Entity tag): An HTTP header holding an identifier for a specific version of a resource, such as a hash of its content. A client sends it back in If-None-Match to ask whether it changed, and can also use it to avoid overwriting newer edits.
ETag: an example
ETag: "v42" is returned; the client later sends If-None-Match: "v42" and receives 304 if nothing changed.
Related terms
More Web APIs HTTP terms
Where you learn it
ETag is part of the AI Engineering Program, which teaches it with notes, a hands-on lab and an exam. The first lesson is free.