What does CORS stand for and why does it occur?

CORS stands for Cross-Origin Resource Sharing. It's a security mechanism implemented by web browsers to prevent malicious websites from making requests to other domains. It occurs when a web page (usually a JavaScript page) attempts to access a resource (like an image, script, or API endpoint) on a different domain than the one the page is hosted on. The browser blocks this request unless the server hosting the resource explicitly allows it (sets CORS headers).