Echolocation is a way of locating objects by sending out a signal and analyzing the echoes that return. In cybersecurity, it is often used as an analogy for active reconnaissance: a scanner or attacker probes a system and studies the responses to infer live hosts, open services, timing, or network layout.
It matters because those “reflections” can reveal information that was not meant to be public. Response codes, banner text, packet timing, and error messages can all help map a target. Defenders use the same idea to spot scanning, detect unusual probing, and verify that systems respond only as intended. The practical lesson is simple: even a small response can become useful intelligence when many probes are sent.