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HTTP headers - Basics

HTTP headers

HTTP headers are key-value pairs sent in an HTTP request or response that provide additional information about the resource being requested or the data being sent. Some common HTTP headers and their uses include:

Accept: Specifies the preferred format of the response, such as "application/json" for a JSON response. This header helps the server determine the best format to return the data in.

Content-Type: Specifies the format of the data being sent in the request body, such as "application/json" for JSON data. This header helps the server understand the format of the data being sent in the request.

Authorization: Used to provide authentication information, such as a token or credentials. This header allows the server to validate the request and ensure that the client has permission to access the requested resource.

User-Agent: Provides information about the client making the request, such as the type of browser or operating system. This header helps the server understand the client and respond appropriately.

Referer: Indicates the URL of the resource from which the request originated. This header helps the server track where the request is coming from and understand the context of the request.

If-Modified-Since: Makes the request conditional, only returning the response if the resource has been modified since the specified date. This header helps the client avoid unnecessary data transfers by only requesting updated data.

Cache-Control: Specifies the cache-related headers that control the caching of the response. This header helps the client determine how long the response should be cached and whether to retrieve it from cache or from the server.

Location: Specifies the URL of a newly created resource, used in response to a POST request. This header helps the client find the newly created resource and perform additional operations on it if necessary.

These headers provide important information about the request or response, helping the client and server communicate effectively. RESTful APIs often use headers to provide additional context for each request, allowing the server to better understand and respond to the request.

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