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| Header | Description | Example |
|---|---|---|
| Accept | Specifies the content types that the client is able to receive. | Accept: text/plain, text/html |
| Accept-Charset | Character sets that the browser can accept. | Accept-Charset: iso-8859-5 |
| Accept-Encoding | Specifies the content encoding types that the browser can support from the web server. | Accept-Encoding: compress, gzip |
| Accept-Language | Languages that the browser can accept. | Accept-Language: en,zh |
| Accept-Ranges | Indicates if the server accepts requests for partial content. | Accept-Ranges: bytes |
| Authorization | Authorization credentials for HTTP authorization. | Authorization: Authorization credentials |
| Cache-Control | Specifies caching directives for requests and responses. | Cache-Control: no-cache |
| Connection | Specifies whether the client requires a persistent connection. (HTTP 1.1 assumes persistent connections by default) | Connection: close |
| Cookie | Contains stored cookies for the requested domain, sent to the web server with the request. | Cookie: $Version=1; Skin=new; |
| Content-Length | The length of the request body in bytes. | Content-Length: 348 |
| Content-Type | MIME type of the body of the request. | Content-Type: application/x-www-form-urlencoded |
| Date | The date and time the request was sent. | Date: Tue, 15 Nov 2010 08:12:31 GMT |
| Expect | Indicates a specific server behavior expected by the client. | Expect: 100-continue |
| From | Email address of the user making the request. | From: [email protected] |
| Host | The domain name and port number of the server receiving the request. | Host: noxtoolbox.com |
| If-Match | Only performs the request if the resource matches the given ETag. | If-Match: “specific value” |
| If-Modified-Since | Performs the request only if the resource has been modified since the specified date. | If-Modified-Since: Sat, 29 Oct 2010 19:43:31 GMT |
| If-None-Match | Returns a 304 status if the resource has not changed; the value compares the server's ETag to determine changes. | If-None-Match: “specific value” |
| If-Range | If the entity has not changed, the server sends the missing part; otherwise, it sends the entire new entity. Also uses ETag. | If-Range: “specific value” |
| If-Unmodified-Since | Performs the request only if the resource has not been modified since the specified date. | If-Unmodified-Since: Sat, 29 Oct 2010 19:43:31 GMT |
| Max-Forwards | Limits the number of times the message can be forwarded through proxies and gateways. | Max-Forwards: 10 |
| Pragma | Contains implementation-specific directives. | Pragma: no-cache |
| Proxy-Authorization | Authorization credentials for connecting to a proxy. | Proxy-Authorization: credentials for proxy authorization |
| Range | Requests only a specific portion of an entity. | Range: bytes=500-999 |
| Referer | The address of the previous web page from which a request is made. | Referer: http://noxtoolbox.com |
| TE | Indicates the transfer encodings the client is willing to accept and if it accepts trailer fields. | TE: trailers,deflate;q=0.5 |
| Upgrade | Specifies additional communication protocols supported by the client. | Upgrade: HTTP/2.0, SHTTP/1.3, IRC/6.9, RTA/x11 |
| User-Agent | Contains information about the user agent (browser) originating the request. | User-Agent: Mozilla/5.0 (Linux; X11) |
| Via | Informs about intermediate proxies or gateways used to send the request. | Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1) |
| Warning | Provides additional information about potential issues with the entity. | Warn: 199 Miscellaneous warning |
| Header | Description | Example |
|---|---|---|
| Accept-Ranges | Indicates if the server accepts range requests and which type. | Accept-Ranges: bytes |
| Age | Estimated time (in seconds) that has elapsed since the response was generated by the origin server. | Age: 12 |
| Allow | Lists valid actions for a specified resource. If not allowed, returns 405. | Allow: GET, HEAD |
| Cache-Control | Instructs all caching mechanisms whether they can cache the response and the type of caching. | Cache-Control: no-cache |
| Content-Encoding | Content encoding types supported by the web server. | Content-Encoding: gzip |
| Content-Language | The language of the response body. | Content-Language: en,zh |
| Content-Length | The length of the response body in bytes. | Content-Length: 348 |
| Content-Location | An alternate location for the requested resource. | Content-Location: /index.htm |
| Content-MD5 | The MD5 checksum of the response body. | Content-MD5: MD5 checksum |
| Content-Range | Specifies where in the full body the partial response belongs. | Content-Range: bytes 21010-47021/47022 |
| Content-Type | The MIME type of the response content. | Content-Type: text/html; charset=utf-8 |
| Date | The date and time the message was sent from the original server. | Date: Tue, 15 Nov 2010 08:12:31 GMT |
| ETag | The current value of the entity tag for the requested variable. | ETag: “current value of entity tag” |
| Expires | The date and time the response is expected to expire. | Expires: Thu, 01 Dec 2010 16:00:00 GMT |
| Last-Modified | The last modification date of the requested resource. | Last-Modified: Tue, 15 Nov 2010 12:45:26 GMT |
| Location | Used to redirect the recipient to a location other than the request URL to complete the request or identify a new resource. | Location: http://noxtoolbox.com |
| Pragma | Contains implementation-specific directives that can be applied to any recipient along the response chain. | Pragma: no-cache |
| Proxy-Authenticate | Indicates the authentication scheme and parameters applicable to the proxy URL. | Proxy-Authenticate: Basic |
| refresh | Used to redirect or notify that a new resource has been created after a specified time (e.g., 5 seconds). Proposed by Netscape, supported by most browsers. |
Refresh: 5; url= http://noxtoolbox.com
|
| Retry-After | If the entity is temporarily unavailable, informs the client to retry after a specified time. | Retry-After: 120 |
| Server | The name of the web server software. | Server: Apache/1.3.27 (Unix) (Red-Hat/Linux) |
| Set-Cookie | Sets an HTTP cookie. | Set-Cookie: UserID=JohnDoe; Max-Age=3600; Version=1 |
| Trailer | Indicates that the header fields are at the end of a chunked transfer encoding. | Trailer: Max-Forwards |
| Transfer-Encoding | Specifies the form of encoding used to safely transfer the payload body to the user. | Transfer-Encoding:chunked |
| Vary | Informs downstream proxies whether they should use a cached response or request a new one from the original server. | Vary: * |
| Via | Indicates through which intermediary (proxy/gateway) the client response was sent. | Via: 1.0 fred, 1.1 nowhere.com (Apache/1.1) |
| Warning | Provides warnings about potential issues with the entity. | Warning: 199 Miscellaneous warning |
| WWW-Authenticate | Indicates the authentication scheme that should be used to access the requested entity. | WWW-Authenticate: Basic |
HTTP headers provide information about the request, response, or other sending entity. They include general headers, request headers, response headers, and entity headers.
Each header field consists of a name, a colon (:), and a field value.
General headers: Used for both requests and responses, associated with the overall message rather than a specific resource.
Request headers: Allow the client to pass information about itself and its desired response form.
Response headers: Used by the server to provide information about itself.
Entity headers: Define information about the resource being transferred; can be used for both requests and responses.