Concept
The status code tells the client what happened: 2xx success, 3xx redirect, 4xx the client's mistake, 5xx the server's. Choosing the right one lets clients and proxies behave correctly without reading the body.
The tutor works through these with you, in conversation and code. A session ends when you have shown them, not when a video does.
A few lines that show Status codes doing its job.
200 OK a read or an update succeeded
201 Created something new exists; Location header points to it
204 No Content done, nothing to return (a delete)
400 Bad Request the request is malformed or fails validation
401 Unauthorized no valid credentials
403 Forbidden valid credentials, not allowed
404 Not Found no such resource (or hide that it exists)
409 Conflict the change clashes with current state
429 Too Many Requests
500 Internal Server Error a bug; never the client's faultReturning 200 with { "error": "not found" } in the body. Caches store it as a success, clients retry logic is skipped, and monitoring sees a healthy endpoint.
Your roadmap puts these before Status codes, unless you already know them.
Once a session shows you understand Status codes, it comes back for review. Each review takes a minute and tells the memory model how well you still know it.
Topics that build on Status codes.