HTTP headers 分类
| Family | Request | Response |
|---|---|---|
| Caching | Cache-Control Pragma (HTTP/1.0) | Cache-Control Expires (HTTP/1.0) |
| Caching (conditional) | If-None-Match If-Modified-Since If-Unmodified-Since | ETag Last-Modified Vary |
| Referrer | Referer (祖传拼写错误) | Referrer-Policy |
| CORS | Origin Access-Control-Request-Method Access-Control-Request-Headers | Access-Control-Allow-Origin Access-Control-Expose-Headers Access-Control-Max-Age Access-Control-Allow-Credentials Access-Control-Allow-Methods Access-Control-Allow-Headers |