What is EDR? Endpoint detection and response explained

What EDR actually is

EDR stands for endpoint detection and response. In plain terms, it is security software that lives on your endpoints, the laptops, servers, and workstations people use, and continuously watches what each device is doing so it can spot an attack and help you respond. The word that matters most is endpoint: EDR works by placing a small program, called an agent, on each device it protects, and that agent is its eyes and hands.

It helps to understand where EDR came from. For years, the standard defense was antivirus, which worked by keeping a list of known-bad files, signatures, and blocking anything that matched. That worked until attackers started changing their malware constantly and running attacks that used no malicious file at all. Antivirus, looking only for known signatures, missed them. EDR was the industry's answer: instead of asking only is this a known-bad file, it asks is this device behaving the way it should. That shift from signatures to behavior is the essence of what EDR is.

EDR versus antivirus: the key difference

People often use the terms interchangeably, but the difference is real and worth understanding. Traditional antivirus is largely preventive and signature-based: it tries to block known threats at the door. EDR is detective and behavioral: it assumes something might get in, watches continuously for the behavior of an attack, and gives you the tools to investigate and respond when it sees it. Most modern endpoint products combine both, antivirus-style prevention plus EDR-style detection and response, which is why you sometimes hear the umbrella term endpoint protection platform.

The practical upshot is that EDR can catch things antivirus cannot: a brand-new strain with no known signature, or a file-less attack that abuses legitimate tools already on the machine. In exchange, EDR generates far more data and requires someone, a security team or a managed service, to investigate what it surfaces.

How EDR works, step by step

Under the hood, every EDR product follows the same basic loop. Understanding it demystifies the category.

• Collect: the agent on each endpoint continuously records activity, the processes that run, the files they open, network connections, registry changes, and user logins.
• Analyze: that telemetry is checked against known attack signatures and, more importantly, against behavioral models that flag activity resembling an attack, such as a process trying to encrypt many files at once.
• Detect: when something crosses a threshold, EDR raises an alert, ideally with context about what happened and how serious it looks.
• Investigate: responders use the recorded telemetry to trace the attack, what started it, what it touched, and how far it spread, which is the response half of the name.
• Respond: EDR can take action, isolating the endpoint from the network, killing a malicious process, or quarantining a file, to stop the attack on that device.

What EDR protects, and what it does well

EDR is genuinely valuable, and any serious security program should have it. On the devices it covers, it provides deep visibility that nothing else matches: it can see exactly what a process did, reconstruct the chain of an attack, and give responders the evidence to understand and contain it. It catches both known malware and many novel, behavior-based attacks that signature tools miss, and it can respond in an automated way on the endpoint, isolating a compromised laptop in seconds.

For a fleet of managed computers, laptops, servers, and workstations that the organization controls and can install software on, EDR is close to essential. If your environment were only those devices, EDR would take you a long way toward a solid defense.

Where EDR reaches its limits

EDR's great strength, that it lives on the device, is also the source of its two defining limits, and both matter a great deal in environments like healthcare.

The first limit is coverage. EDR only exists where its agent can be installed. A huge class of connected devices cannot host one: medical equipment, industrial control systems, and much legacy and embedded hardware run closed or unsupported operating systems that forbid third-party software. Research has found that while roughly half of connected medical devices run a version of Windows, only about 10% carry active anti-malware protection. To EDR, the rest are simply invisible, which is exactly why attackers favor those devices as entry points.

The second limit is that detection is not continuity or recovery. EDR's job is to detect a threat and help you respond to it on an endpoint. It is not designed to keep an organization running through an attack, to contain a threat across a whole network in a safety-aware way, or to restore systems after encryption. When an attack does get through, EDR tells you it happened; it does not, by itself, bring you back.

Do you still need EDR?

Yes. Nothing here is an argument against EDR. It is a foundational layer, and removing it would be a mistake. The point is simply that EDR is one layer, not the whole answer, and knowing its limits lets you build a defense that covers them. In a device-heavy environment, you pair EDR with two things it cannot provide: coverage for the devices it cannot run on, and the ability to keep operating and recover when an attack lands.

That is how we fit. We are not another endpoint agent competing with your EDR, we sit alongside it and cover what it cannot: agentless protection for the connected devices it is blind to, containment that stops an attack across the network, and self-healing recovery from immutable backups. If you want to go deeper, our pillar on why EDR alone is not enough explains the gaps in detail, our guide to EDR vs XDR vs MDR vs NDR sorts out the related acronyms, and our look at evasive ransomware