(/en-US/docs/Web/HTTP/Headers/WWW-Authenticate)
    131. [ ` X-Content-Type-Options ` ](/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options)
    132. [ ` X-DNS-Prefetch-Control ` ](/en-US/docs/Web/HTTP/Headers/X-DNS-Prefetch-Control) Non-standard 
    133. [ ` X-Forwarded-For ` ](/en-US/docs/Web/HTTP/Headers/X-Forwarded-For) Non-standard 
    134. [ ` X-Forwarded-Host ` ](/en-US/docs/Web/HTTP/Headers/X-Forwarded-Host) Non-standard 
    135. [ ` X-Forwarded-Proto ` ](/en-US/docs/Web/HTTP/Headers/X-Forwarded-Proto) Non-standard 
    136. [ ` X-Frame-Options ` ](/en-US/docs/Web/HTTP/Headers/X-Frame-Options)
    137. [ ` X-XSS-Protection ` ](/en-US/docs/Web/HTTP/Headers/X-XSS-Protection) Non-standard 
  19. HTTP request methods 
    1. [ ` CONNECT ` ](/en-US/docs/Web/HTTP/Methods/CONNECT)
    2. [ ` DELETE ` ](/en-US/docs/Web/HTTP/Methods/DELETE)
    3. [ ` GET ` ](/en-US/docs/Web/HTTP/Methods/GET)
    4. [ ` HEAD ` ](/en-US/docs/Web/HTTP/Methods/HEAD)
    5. [ ` OPTIONS ` ](/en-US/docs/Web/HTTP/Methods/OPTIONS)
    6. [ ` PATCH ` ](/en-US/docs/Web/HTTP/Methods/PATCH)
    7. [ ` POST ` ](/en-US/docs/Web/HTTP/Methods/POST)
    8. [ ` PUT ` ](/en-US/docs/Web/HTTP/Methods/PUT)
    9. [ ` TRACE ` ](/en-US/docs/Web/HTTP/Methods/TRACE)
  20. HTTP response status codes 
    1. [ ` 100 Continue ` ](/en-US/docs/Web/HTTP/Status/100)
    2. [ ` 101 Switching Protocols ` ](/en-US/docs/Web/HTTP/Status/101)
    3. [ ` 102 Processing ` ](/en-US/docs/Web/HTTP/Status/102)
    4. [ ` 103 Early Hints ` ](/en-US/docs/Web/HTTP/Status/103)
    5. [ ` 200 OK ` ](/en-US/docs/Web/HTTP/Status/200)
    6. [ ` 201 Created ` ](/en-US/docs/Web/HTTP/Status/201)
    7. [ ` 202 Accepted ` ](/en-US/docs/Web/HTTP/Status/202)
    8. [ ` 203 Non-Authoritative Information ` ](/en-US/docs/Web/HTTP/Status/203)
    9. [ ` 204 No Content ` ](/en-US/docs/Web/HTTP/Status/204)
    10. [ ` 205 Reset Content ` ](/en-US/docs/Web/HTTP/Status/205)
    11. [ ` 206 Partial Content ` ](/en-US/docs/Web/HTTP/Status/206)
    12. [ ` 207 Multi-Status ` ](/en-US/docs/Web/HTTP/Status/207)
    13. [ ` 208 Already Reported ` ](/en-US/docs/Web/HTTP/Status/208)
    14. [ ` 226 IM Used ` ](/en-US/docs/Web/HTTP/Status/226)
    15. [ ` 300 Multiple Choices ` ](/en-US/docs/Web/HTTP/Status/300)
    16. [ ` 301 Moved Permanently ` ](/en-US/docs/Web/HTTP/Status/301)
    17. [ ` 302 Found ` ](/en-US/docs/Web/HTTP/Status/302)
    18. [ ` 303 See Other ` ](/en-US/docs/Web/HTTP/Status/303)
    19. [ ` 304 Not Modified ` ](/en-US/docs/Web/HTTP/Status/304)
    20. [ ` 307 Temporary Redirect ` ](/en-US/docs/Web/HTTP/Status/307)
    21. [ ` 308 Permanent Redirect ` ](/en-US/docs/Web/HTTP/Status/308)
    22. [ ` 400 Bad Request ` ](/en-US/docs/Web/HTTP/Status/400)
    23. [ ` 401 Unauthorized ` ](/en-US/docs/Web/HTTP/Status/401)
    24. [ ` 402 Payment Required ` ](/en-US/docs/Web/HTTP/Status/402)
    25. [ ` 403 Forbidden ` ](/en-US/docs/Web/HTTP/Status/403)
    26. [ ` 404 Not Found ` ](/en-US/docs/Web/HTTP/Status/404)
    27. [ ` 405 Method Not Allowed ` ](/en-US/docs/Web/HTTP/Status/405)
    28. [ ` 406 Not Acceptable ` ](/en-US/docs/Web/HTTP/Status/406)
    29. [ ` 407 Proxy Authentication Required ` ](/en-US/docs/Web/HTTP/Status/407)
    30. [ ` 408 Request Timeout ` ](/en-US/docs/Web/HTTP/Status/408)
    31. [ ` 409 Conflict ` ](/en-US/docs/Web/HTTP/Status/409)
    32. [ ` 410 Gone ` ](/en-US/docs/Web/HTTP/Status/410)
    33. [ ` 411 Length Required ` ](/en-US/docs/Web/HTTP/Status/411)
    34. [ ` 412 Precondition Failed ` ](/en-US/docs/Web/HTTP/Status/412)
    35. [ ` 413 Content Too Large ` ](/en-US/docs/Web/HTTP/Status/413)
    36. [ ` 414 URI Too Long ` ](/en-US/docs/Web/HTTP/Status/414)
    37. [ ` 415 Unsupported Media Type ` ](/en-US/docs/Web/HTTP/Status/415)
    38. [ ` 416 Range Not Satisfiable ` ](/en-US/docs/Web/HTTP/Status/416)
    39. [ ` 417 Expectation Failed ` ](/en-US/docs/Web/HTTP/Status/417)
    40. [ ` 418 I'm a teapot ` ](/en-US/docs/Web/HTTP/Status/418)
    41. [ ` 421 Misdirecte