MIME Type / Media Type Registry
Correct Content-Type headers drive content negotiation, browser rendering, and API behavior. Wrong types cause security and parsing bugs.
What It Defines
IANA registry of all registered MIME types (application/json, image/png, video/mp4, text/html, etc.). The Content-Type and Accept headers in HTTP reference these registered types.
Canonical (Normative)
Convenient (Practical)
Authoritative registry for protocol parameters: ports, HTTP status codes, media types, DNS record types, and many other code points. Not a spec body — a registry body.
Related Specs
This is the core contract of every web API, browser request, and server response. You can't design or debug HTTP without knowing this.
Every file upload in your app uses this. Know the MIME boundary, Content-Disposition, and Content-Type mechanics to build and debug file upload APIs.