HTTP headers are fields in the header of an HTTP request or response that provide information about the client or server, the requested resource, or the returned resource. They are used to control various aspects of the communication between a client (e.g. a web browser) and a server (e.g. a web server).
HTTP headers can be grouped into several categories, including:
Request headers: These headers provide information about the client and the resource being requested, such as the client’s preferred language, the type of content being requested, and the user agent (browser) being used.
Response headers: These headers provide information about the server and the resource being returned, such as the date and time the resource was last modified, the type and size of the resource, and the status code of the response.
Entity headers: These headers provide information about the resource being returned, such as its length, content type and encoding.
Commonly used HTTP headers include:
Accept: Specifies the types of content the client will accept in the response.
Content-Type: Specifies the type of content sent in the request or returned in the response.
User-Agent: Specifies the browser or client making the request.
Authorization: Specifies authentication information for the client.
Location: Specifies the URL that the client should be redirected to.
Cache-Control: Specifies how the browser should handle caching of the resource.
Set-Cookie: Sends a cookie from the server to the client.
HTTP headers are an important aspect of the HTTP protocol, and they play a critical role in controlling the client and server’s behavior and ensuring that the correct data is sent and received. They are also used to implement security mechanisms, optimize the application’s performance and support various features, such as cookies, caching and redirection.
Also, See: .htaccess