What it is
Defender for Endpoint reads what actually happens on a device and reports sequences that do not fit. The analysis runs in Microsoft’s cloud, and the signals come from the operating system itself rather than from an agent bolted on afterwards.
What it is for
Estates that are on Microsoft anyway. The practical advantage is rarely detection quality; it is that identity, device management and endpoint security use the same groups and the same console.
What to watch
Two things. Licensing first: the full feature set depends on the plan, and the difference between tiers is exactly the part you miss later. Then the first few weeks: backup agents, monitoring and home-grown scripts all look like attackers to an EDR. Those exceptions belong in writing, or in two years there is a rule set nobody wants to touch.
