Cross-Origin Resource Sharing (CORS) is a web security mechanism that regulates cross-origin requests made by frontend JavaScript code to APIs hosted on different origins, often leading to errors if not properly configured, especially in web applications where the frontend and backend are on separate domains. Common CORS errors include missing or mismatched `Access-Control-Allow-Origin` headers, requests not using HTTP/HTTPS protocols, and multiple headers being sent, each with specific solutions such as adjusting server responses or ensuring correct request handling. While there are ways to bypass CORS, such as disabling browser security, using extensions, or employing proxies, these methods carry security risks and should only be used temporarily during development. Proper CORS implementation on backend servers is crucial to avoid potential vulnerabilities like cross-site request forgery (CSRF) and to ensure seamless operation without needing to bypass security measures. Understanding CORS and its common errors equips developers with the knowledge to effectively manage and resolve issues, enhancing both application functionality and security.