Cross-Origin Resource Sharing (CORS) is a mechanism that allows web pages to request resources from a different domain than the one that served the web page. This is a security feature that restricts a web page from making requests to a different domain than the one that served the page.
CORS works by adding HTTP headers to the server's response, which indicate which domains are allowed to make requests to the server. The browser then checks the response headers before making the request, and will only continue with the request if the response headers indicate that the request is allowed.
For example, if a web page served from "example.com" wants to make a request to "api.example.com," the server at "api.example.com" needs to include the appropriate CORS headers in its response. The headers might look something like this:
Access-Control-Allow-Methods: GET, POST, PUT
In this example, the headers indicate that the server at "api.example.com" is allowing requests from "example.com," and the allowed methods are "GET," "POST," and "PUT."
CORS is an important security feature, but it can also be a source of frustration for developers who are trying to make cross-domain requests. If the appropriate headers are not included in the server's response, the browser will block the request and the user will see an error.
MDN Web Docs: https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS
HTML5 Rocks: https://www.html5rocks.com/en/tutorials/cors/
Enable CORS: https://enable-cors.org/
YouTube tutorials: There are many video tutorials available on YouTube that cover CORS, you can search for "CORS tutorial" or "CORS with [your preferred programming language]" to find relevant content.
I hope these resources help you learn more about CORS and how to implement it.