[ Protocol upgrade mechanism ](/en-US/docs/Web/HTTP/Protocol_upgrade_mechanism)
  5. HTTP security 
    1. [ Content Security Policy (CSP) ](/en-US/docs/Web/HTTP/CSP)
    2. [ HTTP Strict Transport Security (HSTS) ](/en-US/docs/Web/HTTP/Headers/Strict-Transport-Security)
    3. [ X-Content-Type-Options ](/en-US/docs/Web/HTTP/Headers/X-Content-Type-Options)
    4. [ X-Frame-Options ](/en-US/docs/Web/HTTP/Headers/X-Frame-Options)
    5. [ X-XSS-Protection ](/en-US/docs/Web/HTTP/Headers/X-XSS-Protection)
    6. [ Mozilla web security guidelines ](https://wiki.mozilla.org/Security/Guidelines/Web_Security)
    7. [ Mozilla Observatory ](https://observatory.mozilla.org/)
  6. [ HTTP access control (CORS) ](/en-US/docs/Web/HTTP/CORS)
  7. [ HTTP authentication ](/en-US/docs/Web/HTTP/Authentication)
  8. [ HTTP caching ](/en-US/docs/Web/HTTP/Caching)
  9. [ HTTP compression ](/en-US/docs/Web/HTTP/Compression)
  10. [ HTTP conditional requests ](/en-US/docs/Web/HTTP/Conditional_requests)
  11. [ HTTP content negotiation ](/en-US/docs/Web/HTTP/Content_negotiation)
  12. [ HTTP cookies ](/en-US/docs/Web/HTTP/Cookies)
  13. [ HTTP range requests ](/en-US/docs/Web/HTTP/Range_requests)
  14. [ HTTP redirects ](/en-US/docs/Web/HTTP/Redirections)
  15. [ HTTP specifications ](/en-US/docs/Web/HTTP/Resources_and_specifications)
  16. [ Permissions Policy ](/en-US/docs/Web/HTTP/Permissions_Policy)
  17. References 
  18. HTTP headers 
    1. [ ` Accept ` ](/en-US/docs/Web/HTTP/Headers/Accept)
    2. [ ` Accept-CH ` ](/en-US/docs/Web/HTTP/Headers/Accept-CH)
    3. [ ` Accept-CH-Lifetime ` ](/en-US/docs/Web/HTTP/Headers/Accept-CH-Lifetime) Non-standard  Deprecated 
    4. [ ` Accept-Charset ` ](/en-US/docs/Web/HTTP/Headers/Accept-Charset)
    5. [ ` Accept-Encoding ` ](/en-US/docs/Web/HTTP/Headers/Accept-Encoding)
    6. [ ` Accept-Language ` ](/en-US/docs/Web/HTTP/Headers/Accept-Language)
    7. [ ` Accept-Patch ` ](/en-US/docs/Web/HTTP/Headers/Accept-Patch)
    8. [ ` Accept-Post ` ](/en-US/docs/Web/HTTP/Headers/Accept-Post)
    9. [ ` Accept-Ranges ` ](/en-US/docs/Web/HTTP/Headers/Accept-Ranges)
    10. [ ` Access-Control-Allow-Credentials ` ](/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Credentials)
    11. [ ` Access-Control-Allow-Headers ` ](/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Headers)
    12. [ ` Access-Control-Allow-Methods ` ](/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Methods)
    13. [ ` Access-Control-Allow-Origin ` ](/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin)
    14. [ ` Access-Control-Expose-Headers ` ](/en-US/docs/Web/HTTP/Headers/Access-Control-Expose-Headers)
    15. [ ` Access-Control-Max-Age ` ](/en-US/docs/Web/HTTP/Headers/Access-Control-Max-Age)
    16. [ ` Access-Control-Request-Headers ` ](/en-US/docs/Web/HTTP/Headers/Access-Control-Request-Headers)
    17. [ ` Access-Control-Request-Method ` ](/en-US/docs/Web/HTTP/Headers/Access-Control-Request-Method)
    18. [ ` Age ` ](/en-US/docs/Web/HTTP/Headers/Age)
    19. [ ` Allow ` ](/en-US/docs/Web/HTTP/Headers/Allow)
    20. [ ` Alt-Svc ` ](/en-US/docs/Web/HTTP/Headers/Alt-Svc)
    21. [ ` Alt-Used ` ](/en-US/docs/Web/HTTP/Headers/Alt-Used)
    22. [ ` Authorization ` ](/en-US/docs/Web/HTTP/Headers/Authorization)
    23. [ ` Cache-Control ` ](/en-US/docs/Web/HTTP/Headers/Cache-Control)
    24. [ ` Clear-Site-Data ` ](/en-US/docs/Web/HTTP/Headers/Clear-Site-Data)
    25. [ ` Connection ` ](/en-US/docs/Web/HTTP/Headers/Connection)
    26. [ ` Content-Digest ` ](/en-US/docs/Web/HTTP/Headers/Content-Digest) Experimental 
    27. [ ` Content-Disposition ` ](/en-US/docs/Web/HTTP/Headers/Content-Disposition)
    28. [ ` Content-DPR ` ](/en-US/docs/Web/HTTP/Headers/Content-DPR) Non-standard  Deprecated 
    29. [ ` Content-Encoding ` ](/en-US/docs/Web/HTTP/Headers/Content-Encoding)
    30. [ ` Content-Language ` ](/en-US/docs/Web/HTTP/Headers/Content-Language)
    31. [ ` Content-Length ` ](/en-US/docs/Web/HTTP/Headers/Content-Length)
    32. [ `