EDR is the acronym for Endpoint Detection and Response, which is sometimes referred to as Endpoint Threat Detection and Response (ETDR). In security terms, the endpoint is a computer, mobile phone, server, or other type of electronic device. Detection is the discovery of an attempted cyber attack on an endpoint. Response is the action taken to thwart or mitigate that particular attack.
An Endpoint Detection and Response system is a software solution that monitors and detects threats and responds automatically to block or contain the threat.