The same-origin policy is a security feature implemented by web browsers to prevent web pages from making requests to a different domain than the one that served the web page. This policy is designed to prevent attackers from making unauthorized requests to a server on behalf of a user.  The same-origin policy is implemented by comparing the origin of a web page (the domain, protocol, and port) to the origin of the requested resource. If the origins match, the request is allowed. If the origins do not match, the request is blocked.  There are a few exceptions to the same-origin policy, including:  Web pages can use the "Access-Control-Allow-Origin" header to allow resources to be accessed from other domains.  Web pages can use the "XMLHttpRequest" object to make requests to a different domain if the server allows it.  Web pages can use "JSONP" (JSON with Padding) to make requests to a different domain if the server allows it.  Overall, the same-origin policy is an important security feature that helps to prevent unauthorized requests from being made to servers on behalf of a user. It is an important consideration when working with web applications, and it is important to ensure that requests are properly authorized and secure.