Build a useful mental model of HTTP
Start with what travels between a client and server, then connect that foundation to browsers, intermediaries, caching, and modern HTTP versions.
Follow the learning path
Read in order for a complete introduction, or start at a known concept. Each guide names the exact prerequisites to revisit.
Step 1 · beginner
Understand the HTTP request-response cycle
Learn the roles, direction, and observable boundaries of a single HTTP request and response.
8 minute lessonStep 2 · beginner
Read HTTP messages without guessing
Read the parts of an HTTP message and know which details are shared across HTTP versions.
9 minute lessonStep 3 · beginner
Choose an HTTP method by its semantics
Choose methods from their defined semantics and understand why retries and redirects treat them differently.
11 minute lessonStep 4 · beginner
Interpret HTTP status codes in context
Use the status class for orientation, then the exact code and request method for the response meaning.
10 minute lessonStep 5 · beginner
Connect HTTP fields to representations
Read HTTP fields as typed metadata and connect selected representations to media types and negotiation.
12 minute lessonStep 6 · intermediate
Predict HTTP redirects and method handling
Predict a redirect by reading its status, Location value, original method, and client behavior together.
11 minute lessonStep 7 · intermediate
Understand HTTP caching and validation
Follow the decisions a cache makes from storage through freshness and validator-based reuse.
15 minute lessonStep 8 · intermediate
Separate cookies, origins, and sites
Keep host and path cookie scope distinct from origin and same-site browser boundaries.
14 minute lessonStep 9 · intermediate
Understand the browser CORS flow
CORS is a browser response-sharing protocol layered on HTTP, not proof that the network request failed.
14 minute lessonStep 10 · intermediate
Find the TLS boundaries around HTTP
TLS protects one connection between peers; trace each termination point before reasoning about end-to-end visibility.
10 minute lessonStep 11 · intermediate
Trace HTTP through proxies and CDNs
Treat every intermediary as a possible HTTP peer and identify the hop that produced an observation.
13 minute lessonStep 12 · intermediate
Separate HTTP semantics from protocol versions
HTTP versions carry shared semantics through different framing, compression, multiplexing, and transport mechanisms.
13 minute lesson