Error responses are messages generated by a system when it encounters a problem while processing a request. These responses help users understand what went wrong, often including an error code and a brief description. Common examples include 404 Not Found, which indicates that a requested resource is unavailable, and 500 Internal Server Error, signaling a problem on the server side. Error responses are essential for troubleshooting and improving user experience. They guide developers in identifying issues within their applications and can help users take corrective actions. By providing clear and informative error messages, systems can enhance communication and reduce frustration.