HTTP fundamentals

Every web app is just programs talking over HTTP. requests is the standard Python client — clean API, sensible defaults.

The verbs you'll actually use

• GET — read. Query string via params=.
• POST — create / submit. Body via json= (auto-sets Content-Type) or data= (form-encoded).
• PUT / PATCH — update.
• DELETE — remove.

Reading the response

• r.status_code — 200 OK, 404 not found, 500 server error, 401 unauth, 429 rate-limited.
• r.json() — parse JSON body (raises if not JSON).
• r.text — raw string body.
• r.headers — response headers dict.

Things that bite

• Always set a timeout: requests.get(url, timeout=10). Otherwise a hung server hangs your program.
• Use r.raise_for_status() to turn 4xx/5xx into exceptions instead of silently succeeding.
• Session pooling: s = requests.Session() — reuses TCP connections, huge speedup for many calls to the same host.

Try it

1. Call https://httpbin.org/status/500 and observe the status_code.
2. Set a header {"X-PyRun": "hello"} and echo it back from /headers.