HTTP Status Code Flashcards: Meanings, Classes & Use Cases
Learn registered HTTP response status codes by number, reason phrase, class, and practical use case, with current IANA and RFC references.
על החפיסה הזו
Learn the current IANA-registered HTTP response status codes as a practical recall system, not a loose cheat sheet.
What this deck practices
- Code → meaning: all 61 response codes assigned in the IANA registry snapshot used on 25 August 2026, starting with the registered reason phrase and a concise RFC-based explanation.
- Meaning → code: 27 selective reverse cards for common, atomic retrieval targets. These are not mechanical reversals of every entry.
- Class purpose: exactly five cards for 1xx Informational, 2xx Successful, 3xx Redirection, 4xx Client Error, and 5xx Server Error.
- Confusion sets: 401 vs 403; 301/302/307/308; 409 vs 422; 404 vs 410; 202 vs 204; and 502 vs 504.
The order introduces the five classes and common responses first, broadens through the registered set, and finishes with comparison and reference material. Forward and reverse variants are separated so one card does not immediately reveal another.
Special registry status
Temporary 104 Upload Resumption Supported is clearly marked with IANA’s recorded expiry of 13 November 2026. HTTP 402 is taught as registered but reserved by RFC 9110 for future use. Unused 306 and 418, plus obsoleted 510, live in a separate reference section rather than the ordinary recall sequence. Unassigned codes and ranges are excluded because they have no registered reason phrase or stable meaning to recall. Deprecated 305 is labeled accurately.
Explanations follow the IANA HTTP Status Code Registry and its linked RFC references. Reason phrases are labels, not complete normative semantics. Examples and comparisons are original paraphrases and do not prescribe one universal REST API design.
This is an independent, unofficial educational deck by Flashcards Open Source App. It is not affiliated with, endorsed by, or produced by IANA, the IETF, or the RFC Editor. No competitor deck, RFC prose, copyrighted table, or exam question was copied. The CC0 label applies to the original prompts, explanations, organization, metadata, and generated cover to the extent applicable rights exist; it does not claim ownership of facts or standards text.
הכרטיסים בחפיסה הזו
כרטיס 1
שאלה
What is the purpose of the 1xx HTTP status-code class?
תשובה
Informational. A 1xx response is interim: it communicates connection status or request progress before the final response.
כרטיס 2
שאלה
What is the purpose of the 2xx HTTP status-code class?
תשובה
Successful. A 2xx response means the request was successfully received, understood, and accepted.
כרטיס 3
שאלה
What is the purpose of the 3xx HTTP status-code class?
תשובה
Redirection. A 3xx response means the user agent needs to take further action to fulfill the request, such as following another URI or using a cached representation.
כרטיס 4
שאלה
What is the purpose of the 4xx HTTP status-code class?
תשובה
Client Error. A 4xx response means the client appears to have made an error; it does not prove that every fault lies in client code.
כרטיס 5
שאלה
What is the purpose of the 5xx HTTP status-code class?
תשובה
Server Error. A 5xx response means the server knows it has erred or cannot perform the requested method.
כרטיס 6
שאלה
What does HTTP status code 200 mean?
תשובה
OK. The request succeeded; the meaning of any response content depends on the request method.
כרטיס 7
שאלה
What does HTTP status code 404 mean?
תשובה
Not Found. The origin server has no current representation for the target resource, or it is unwilling to disclose that one exists. The code does not say whether the condition is temporary or permanent.
כרטיס 8
שאלה
What does HTTP status code 301 mean?
תשובה
Moved Permanently. The target resource has a new permanent URI. For historical reasons, a user agent may change POST to GET when following it; use 308 when method preservation matters.
כרטיס 9
שאלה
What does HTTP status code 500 mean?
תשובה
Internal Server Error. The server hit an unexpected condition that prevented it from fulfilling the request.
כרטיס 10
שאלה
What does HTTP status code 201 mean?
תשובה
Created. The request was fulfilled and created one or more resources. The primary resource is identified by
Location, or by the target URI whenLocationis absent.כרטיס 11
שאלה
What does HTTP status code 401 mean?
תשובה
Unauthorized. The request was not applied because it lacks valid authentication credentials for the target resource. The response includes a
WWW-Authenticatechallenge.כרטיס 12
שאלה
What does HTTP status code 503 mean?
תשובה
Service Unavailable. The server is temporarily unable to handle the request, often because of overload or maintenance. It may send
Retry-After.כרטיס 13
שאלה
What does HTTP status code 204 mean?
תשובה
No Content. The server successfully fulfilled the request and has no additional response content to send.
כרטיס 14
שאלה
What does HTTP status code 403 mean?
תשובה
Forbidden. The server understood the request but refuses to fulfill it. Credentials may be insufficient, or the refusal may be unrelated to authentication.
כרטיס 15
שאלה
What does HTTP status code 302 mean?
תשובה
Found. The target resource is temporarily available at another URI, so future requests should still use the original URI. A user agent may change POST to GET when following it.
כרטיס 16
שאלה
What does HTTP status code 400 mean?
תשובה
Bad Request. The server cannot or will not process the request because of a perceived client error, such as malformed syntax, invalid framing, or deceptive routing.
כרטיס 17
שאלה
What does HTTP status code 502 mean?
תשובה
Bad Gateway. A server acting as a gateway or proxy received an invalid response from an inbound server while trying to fulfill the request.
כרטיס 18
שאלה
Which HTTP status code has the registered reason phrase “OK”?
תשובה
200 OK. It indicates that the request succeeded.
כרטיס 19
שאלה
What does HTTP status code 202 mean?
תשובה
Accepted. The request was accepted for processing, but processing is incomplete and might not ultimately happen.
כרטיס 20
שאלה
Which HTTP status code has the registered reason phrase “Not Found”?
תשובה
404 Not Found. It means there is no current representation for the target resource, or the server will not disclose one.
כרטיס 21
שאלה
What does HTTP status code 304 mean?
תשובה
Not Modified. A conditional GET or HEAD would otherwise have returned 200, but the condition was false, so the client can use its stored representation. A 304 response has no content.
כרטיס 22
שאלה
Which HTTP status code has the registered reason phrase “Created”?
תשובה
201 Created. It means the fulfilled request created one or more resources.
כרטיס 23
שאלה
Which HTTP status code means the request lacks valid authentication credentials?
תשובה
401 Unauthorized. The response challenges the client to authenticate for the target resource.
כרטיס 24
שאלה
Which HTTP status code has the registered reason phrase “Internal Server Error”?
תשובה
500 Internal Server Error. It covers an unexpected server condition that prevented fulfillment.
כרטיס 25
שאלה
Which HTTP status code means success with no additional response content?
תשובה
204 No Content. The action succeeded, and there is no response content to send.
כרטיס 26
שאלה
Which HTTP status code means the server understood the request but refuses to fulfill it?
תשובה
403 Forbidden. Repeating the same request with the same credentials should not be automatic.
כרטיס 27
שאלה
Which HTTP status code has the registered reason phrase “Moved Permanently”?
תשובה
301 Moved Permanently. Future references should use the new permanent URI.
כרטיס 28
שאלה
Which HTTP status code means the server is temporarily unable to handle the request?
תשובה
503 Service Unavailable. Temporary overload or maintenance are typical reasons.
כרטיס 29
שאלה
Which HTTP status code has the registered reason phrase “Bad Request”?
תשובה
400 Bad Request. The server perceives a client-side problem that prevents or discourages processing.
כרטיס 30
שאלה
Which HTTP status code means a gateway or proxy received an invalid inbound response?
תשובה
502 Bad Gateway. The upstream response arrived, but it was invalid.
כרטיס 31
שאלה
Which HTTP status code has the registered reason phrase “Accepted”?
תשובה
202 Accepted. Processing has been accepted but is not complete.
כרטיס 32
שאלה
Which HTTP status code tells a conditional GET or HEAD to use a stored representation?
תשובה
304 Not Modified. The request condition evaluated false, so the stored representation remains valid for this response.
כרטיס 33
שאלה
What does HTTP status code 100 mean?
תשובה
Continue. The server received the initial part of the request and has not rejected it. With
Expect: 100-continue, the client should continue sending the request content.כרטיס 34
שאלה
What does HTTP status code 206 mean?
תשובה
Partial Content. The server is successfully fulfilling a range request by transferring one or more parts of the selected representation.
כרטיס 35
שאלה
What does HTTP status code 307 mean?
תשובה
Temporary Redirect. The resource is temporarily at another URI, and an automatic redirect must preserve the request method.
כרטיס 36
שאלה
What does HTTP status code 409 mean?
תשובה
Conflict. The request cannot be completed because it conflicts with the target resource’s current state. The client may be able to resolve the conflict and resubmit.
כרטיס 37
שאלה
What does HTTP status code 504 mean?
תשובה
Gateway Timeout. A gateway or proxy did not receive a timely response from an upstream server needed to complete the request.
כרטיס 38
שאלה
What does HTTP status code 101 mean?
תשובה
Switching Protocols. The server accepts the client’s
Upgraderequest and names the protocol that will be used after this response.כרטיס 39
שאלה
Which HTTP status code means a range request succeeded with only part of the representation?
תשובה
206 Partial Content. The response carries one or more requested ranges.
כרטיס 40
שאלה
Which temporary redirect status code requires method preservation?
תשובה
307 Temporary Redirect. An automatic redirect must not change the request method.
כרטיס 41
שאלה
Which HTTP status code means a request conflicts with the target resource’s current state?
תשובה
409 Conflict. The client may be able to resolve the state conflict and try again.
כרטיס 42
שאלה
Which HTTP status code means a gateway timed out waiting for an upstream server?
תשובה
504 Gateway Timeout. The upstream response did not arrive in time.
כרטיס 43
שאלה
What does HTTP status code 102 mean?
תשובה
Processing. This registered interim response says the server accepted the complete request but has not finished processing it; a final response still follows.
כרטיס 44
שאלה
What does HTTP status code 203 mean?
תשובה
Non-Authoritative Information. The request succeeded, but a transforming proxy modified the enclosed content from the origin server’s 200 response.
כרטיס 45
שאלה
What does HTTP status code 308 mean?
תשובה
Permanent Redirect. The resource has a new permanent URI, and an automatic redirect must preserve the request method.
כרטיס 46
שאלה
What does HTTP status code 410 mean?
תשובה
Gone. Access to the target resource is no longer available at the origin server, and the condition is likely permanent.
כרטיס 47
שאלה
What does HTTP status code 501 mean?
תשובה
Not Implemented. The server does not support functionality required to fulfill the request, such as an unrecognized method it cannot support for any resource.
כרטיס 48
שאלה
What does HTTP status code 103 mean?
תשובה
Early Hints. This interim response carries header fields the server is likely to include in the final response, letting the client make safe performance optimizations while it waits.
כרטיס 49
שאלה
What does HTTP status code 205 mean?
תשובה
Reset Content. The request succeeded, and the server wants the user agent to reset the document view that caused the request. The response has no content.
כרטיס 50
שאלה
Which permanent redirect status code requires method preservation?
תשובה
308 Permanent Redirect. Future requests should use the new URI without changing the method during automatic redirection.
כרטיס 51
שאלה
Which HTTP status code says a resource is no longer available and is likely gone permanently?
תשובה
410 Gone. Use 404 when the server does not know whether the absence is permanent.
102 כרטיסים
HTTP Status Code Flashcards: Meanings, Classes & Use Cases
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כרטיס 52
שאלה
Which HTTP status code means the required server functionality is unsupported?
תשובה
501 Not Implemented. It applies when the server cannot support the functionality needed to fulfill the request.
כרטיס 53
שאלה
What does HTTP status code 207 mean?
תשובה
Multi-Status. The response reports status for multiple independent operations, as defined for WebDAV.
כרטיס 54
שאלה
What does HTTP status code 300 mean?
תשובה
Multiple Choices. The target has more than one representation, and the response provides alternatives so the user or user agent can choose.
כרטיס 55
שאלה
What does HTTP status code 405 mean?
תשובה
Method Not Allowed. The origin server knows the request method, but the target resource does not support it. The response includes an
Allowfield.כרטיס 56
שאלה
What does HTTP status code 505 mean?
תשובה
HTTP Version Not Supported. The server does not support, or refuses to support, the major HTTP version used in the request.
כרטיס 57
שאלה
What does HTTP status code 208 mean?
תשובה
Already Reported. Inside a WebDAV multistatus response, it avoids repeatedly enumerating descendants of another binding to the same collection.
כרטיס 58
שאלה
What does HTTP status code 303 mean?
תשובה
See Other. The
LocationURI identifies a different resource that can provide an indirect response; the user agent retrieves it with GET or HEAD.כרטיס 59
שאלה
What does HTTP status code 406 mean?
תשובה
Not Acceptable. The target has no current representation acceptable under the request’s proactive negotiation fields, and the server will not send a default.
כרטיס 60
שאלה
What does HTTP status code 506 mean?
תשובה
Variant Also Negotiates. The server has a transparent content-negotiation configuration error: the chosen variant is itself configured to negotiate.
כרטיס 61
שאלה
What does HTTP status code 226 mean?
תשובה
IM Used. The server fulfilled a GET by returning the result of one or more instance manipulations applied to the current representation, identified in the
IMresponse field.כרטיס 62
שאלה
What does HTTP status code 305 mean?
תשובה
Use Proxy — deprecated. It was defined to direct access through a proxy, but RFC 9110 marks the status code deprecated. New implementations should not rely on it.
כרטיס 63
שאלה
What does HTTP status code 407 mean?
תשובה
Proxy Authentication Required. The client must authenticate to a proxy for this request. The proxy sends a
Proxy-Authenticatechallenge.כרטיס 64
שאלה
What does HTTP status code 507 mean?
תשובה
Insufficient Storage. The server cannot store the representation needed to complete the method. WebDAV defines this as a temporary condition.
כרטיס 65
שאלה
What does HTTP status code 408 mean?
תשובה
Request Timeout. The server did not receive a complete request message within the time it was prepared to wait.
כרטיס 66
שאלה
What does HTTP status code 508 mean?
תשובה
Loop Detected. The server terminated a WebDAV operation after finding an infinite loop while processing a
Depth: infinityrequest.כרטיס 67
שאלה
What does HTTP status code 412 mean?
תשובה
Precondition Failed. One or more conditions in the request fields evaluated to false against the current resource state.
כרטיס 68
שאלה
What does HTTP status code 511 mean?
תשובה
Network Authentication Required. The client must authenticate to gain network access. It is intended for an intercepting proxy, such as a captive portal, not an origin server.
כרטיס 69
שאלה
What does HTTP status code 413 mean?
תשובה
Content Too Large. The server refuses to process the request because its content is larger than the server is willing or able to process.
כרטיס 70
שאלה
What does HTTP status code 411 mean?
תשובה
Length Required. The server refuses the request without a defined
Content-Length; the client can retry with a valid value.כרטיס 71
שאלה
Which HTTP status code means a request precondition evaluated to false?
תשובה
412 Precondition Failed. The method is not applied when the stated condition does not match the resource’s current state.
כרטיס 72
שאלה
Which HTTP status code asks the client to authenticate for network access rather than to the origin server?
תשובה
511 Network Authentication Required. It is designed for intercepting network proxies such as captive portals.
כרטיס 73
שאלה
What does HTTP status code 414 mean?
תשובה
URI Too Long. The server refuses the request because the target URI is longer than it is willing to interpret.
כרטיס 74
שאלה
Which HTTP status code means the request content is too large to process?
תשובה
413 Content Too Large. The refusal is about the size of the request content, not the URI or request headers.
כרטיס 75
שאלה
What does HTTP status code 415 mean?
תשובה
Unsupported Media Type. The origin server refuses the request because its content format is unsupported for this method on the target resource.
כרטיס 76
שאלה
What does HTTP status code 416 mean?
תשובה
Range Not Satisfiable. The requested ranges were rejected because none can be satisfied or because the request contains too many small or overlapping ranges.
כרטיס 77
שאלה
What does HTTP status code 422 mean?
תשובה
Unprocessable Content. The server understands the content type and the syntax is correct, but it cannot process the contained instructions.
כרטיס 78
שאלה
What does HTTP status code 417 mean?
תשובה
Expectation Failed. At least one inbound server could not meet the expectation stated in the request’s
Expectfield.כרטיס 79
שאלה
Which HTTP status code means the request content format is unsupported for the target method?
תשובה
415 Unsupported Media Type. The issue can come from
Content-Type,Content-Encoding, or inspecting the data itself.כרטיס 80
שאלה
What does HTTP status code 421 mean?
תשובה
Misdirected Request. The request reached a server that cannot or will not produce an authoritative response for that target URI on the received connection.
כרטיס 81
שאלה
What does HTTP status code 423 mean?
תשובה
Locked. In WebDAV, the source or destination resource for the method is locked.
כרטיס 82
שאלה
Which HTTP status code means syntactically correct content cannot be processed?
תשובה
422 Unprocessable Content. The content type is understood and the syntax is valid, but the contained instructions cannot be processed.
כרטיס 83
שאלה
What does HTTP status code 424 mean?
תשובה
Failed Dependency. The requested action depended on another action, and that other action failed.
כרטיס 84
שאלה
What does HTTP status code 425 mean?
תשובה
Too Early. The server is unwilling to risk processing a request that might be replayed, such as a request sent in TLS early data.
כרטיס 85
שאלה
What does HTTP status code 429 mean?
תשובה
Too Many Requests. The user sent too many requests in a given time. The response may include
Retry-After.כרטיס 86
שאלה
What does HTTP status code 426 mean?
תשובה
Upgrade Required. The server refuses the current protocol but might perform the request after the client upgrades. The response states the required protocol in
Upgrade.כרטיס 87
שאלה
What does HTTP status code 428 mean?
תשובה
Precondition Required. The origin server requires a conditional request, commonly to prevent a lost update when resource state changes between reading and writing.
כרטיס 88
שאלה
What does HTTP status code 431 mean?
תשובה
Request Header Fields Too Large. The server refuses to process the request because all request headers together, or one particular header, are too large.
כרטיס 89
שאלה
Which HTTP status code is registered for rate limiting?
תשובה
429 Too Many Requests. It indicates too many requests in a given amount of time.
כרטיס 90
שאלה
What does HTTP status code 451 mean?
תשובה
Unavailable For Legal Reasons. Access is denied because of a legal demand. The code does not establish whether the resource exists.
כרטיס 91
שאלה
How do HTTP 401 and 403 differ?
תשובה
401 Unauthorized means the request lacks valid authentication credentials and includes an authentication challenge. 403 Forbidden means the server understood the request but refuses it; credentials may be insufficient or irrelevant to the refusal.
כרטיס 92
שאלה
How do HTTP 301, 302, 307, and 308 differ?
תשובה
301 is permanent and may change POST to GET. 302 is temporary and may change POST to GET. 307 is temporary and preserves the method. 308 is permanent and preserves the method.
כרטיס 93
שאלה
How do HTTP 409 and 422 differ?
תשובה
409 Conflict is about a conflict with the target resource’s current state. 422 Unprocessable Content is about understood, syntactically correct request content whose instructions cannot be processed. Neither code dictates one universal REST API policy.
כרטיס 94
שאלה
Which HTTP status code means access is denied because of a legal demand?
תשובה
451 Unavailable For Legal Reasons. The response can explain the legal demand and who it affects.
כרטיס 95
שאלה
How do HTTP 404 and 410 differ?
תשובה
404 Not Found does not say whether the missing representation is temporary or permanent and can also hide a resource’s existence. 410 Gone says the resource is no longer available and the condition is likely permanent.
כרטיס 96
שאלה
How do HTTP 202 and 204 differ?
תשובה
202 Accepted means processing was accepted but is not complete and may never happen. 204 No Content means the request was successfully fulfilled and there is no additional response content.
כרטיס 97
שאלה
How do HTTP 502 and 504 differ?
תשובה
502 Bad Gateway means the gateway or proxy received an invalid upstream response. 504 Gateway Timeout means it did not receive the needed upstream response in time.
כרטיס 98
שאלה
What does HTTP status code 104 mean, and what is its registry status?
תשובה
Upload Resumption Supported — temporary. It is an informational response indicating resumable-upload support. IANA records registration on 13 November 2024, an extension on 15 September 2025, and expiry on 13 November 2026.
כרטיס 99
שאלה
What does HTTP status code 402 mean?
תשובה
Payment Required — reserved for future use. IANA registers the reason phrase, but RFC 9110 does not define a general operational meaning. Treat application-specific payment uses as conventions, not universal HTTP semantics.
כרטיס 100
שאלה
What is the current registry status of HTTP 306?
תשובה
Unused and reserved. RFC 9110 says 306 was defined previously, is no longer used, and remains reserved. It is not an ordinary redirect code.
כרטיס 101
שאלה
What is the current registry status of HTTP 418?
תשובה
Unused and reserved. IANA does not register “I’m a Teapot” as the current reason phrase. RFC 9110 keeps 418 unavailable for other assignments because the joke code was widely deployed.
כרטיס 102
שאלה
What is the current registry status of HTTP 510?
תשובה
Not Extended — obsoleted. The historical code said an extension policy was not met, but IANA marks it obsoleted after the HTTP extension experiments moved to Historic status.
102 כרטיסים
HTTP Status Code Flashcards: Meanings, Classes & Use Cases
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