HTTP topic

HTTP in browsers

Browsers add origin, cookie, Fetch, cache, redirect, and security rules around HTTP exchanges. This cluster connects protocol semantics to the browser decisions developers can observe and debug.

Recommended foundation

Start here

This entry establishes the shared model used by the references, diagnostics, and experiments below.

Learn

Separate cookies, origins, and sites

Keep host and path cookie scope distinct from origin and same-site browser boundaries.

HTTP in browsers

Learn

1 reviewed entry

intermediate
Understand the browser CORS flow
CORS is a browser response-sharing protocol layered on HTTP, not proof that the network request failed.

HTTP in browsers

Reference

2 reviewed entries

intermediate
Access-Control-Allow-Origin field
Access-Control-Allow-Origin identifies which requesting origin may read a CORS response.
intermediate
Cookie field
Cookie carries the stored name and value pairs selected for one HTTP request.

HTTP in browsers

Troubleshoot

2 reviewed entries

intermediate
A browser does not send a cookie
Diagnose cookie storage and request selection separately from CORS response access.
intermediate
A browser reports a CORS error
Find which CORS flow step failed and preserve the HTTP response evidence the browser received.

HTTP in browsers

Lab

2 reviewed entries

intermediate
Observe a bounded cookie lifecycle
Observe cookie creation, request selection, and cleanup as separate browser steps.
intermediate
Observe a CORS preflight
Run a simple GET and a preflighted POST, then inspect the final response shared with JavaScript.

HTTP in browsers

Glossary

2 reviewed entries

intermediate
CORS preflight request
A CORS preflight is an OPTIONS request asking whether a cross-origin method and request fields are permitted.
beginner
Origin
An origin is the scheme, host, and port tuple associated with a resource or request context.

HTTP in browsers

Start here

Separate cookies, origins, and sites

Learn

Understand the browser CORS flow

Reference

Access-Control-Allow-Origin field

Cookie field

Troubleshoot

A browser does not send a cookie

A browser reports a CORS error

Lab

Observe a bounded cookie lifecycle

Observe a CORS preflight

Glossary

CORS preflight request

Origin