--- title: HTTP reference short-title: Reference slug: Web/HTTP/Reference page-type: listing-page sidebar: httpsidebar --- This page lists HTTP reference documentation on MDN. {{SubPagesWithSummaries}} The following subsections are also notable: - [CSP directives](/en-US/docs/Web/HTTP/Reference/Headers/Content-Security-Policy#directives) - : The {{HTTPHeader("Content-Security-Policy")}} (CSP) response header allows website administrators to specify which resources the user agent is allowed to load for a given page. This section lists directives that can be used in a CSP header, with individual documentation pages that describe how the directives work and how to use them. - [Permissions-Policy directives](/en-US/docs/Web/HTTP/Reference/Headers/Permissions-Policy#directives) - : The {{HTTPHeader("Permissions-Policy")}} response header provides a mechanism to allow or deny the use of browser features in a document or within any {{HTMLElement("iframe")}} element in the document. This section lists directives that can be used in a Permissions-Policy header, with individual documentation pages that describe how the directives work and how to use them.