A Unix-like system is an operating environment that follows Unix design ideas, especially its permission model, process control, and administrative separation. Common examples include Linux, BSD variants, and systems that use similar shell and filesystem conventions.
In cybersecurity, Unix-like systems matter because their security model shapes how software runs and how attackers try to escalate privileges. Services often start with limited rights, then interact with files, accounts, and privileged daemons. If a bug lets an attacker cross that boundary, a simple service flaw can become a full system compromise. Defenders look closely at ownership, setuid behavior, service isolation, and update hygiene, because misconfiguration can weaken even a patched system.