# Cross-Origin Resource Sharing (CORS)

### What is CORS?

CORS is a security feature in web browsers that allows servers to specify which domains are allowed to make requests to them, ensuring the secure transfer of data between different domains.

### Why is CORS Important?

By default, JavaScript running on a web page is not allowed to make requests to a different domain than the one it came from. Therefore, CORS is important to allow cross-domain resource sharing while maintaining security.

### How does CORS Work?

When a browser wants to access a resource from a different domain, it sends a pre-flight request to the domain server using the OPTIONS method to check if the cross-origin request is allowed. If the domain server allows the request, the browser sends a second request with the actual method specified in the original request, and the domain server provides the requested data.

### How to Configure CORS?

To configure CORS, you need to set the Access-Control-Allow-Origin header in the response from the domain server to indicate which domains are allowed to access the resource. You can also set additional headers like Access-Control-Allow-Methods and Access-Control-Allow-Headers to specify which HTTP methods and headers are allowed.