An antivirus scan is a process in which your security software examines files, programs, and system memory on your PC to look for malicious code. When you run an antivirus scan, the software compares files against a database of known malware signatures, applies behavioral analysis to spot suspicious activity, and checks file reputation against cloud intelligence databases.

Modern antivirus software does not rely on a single detection method. A good antivirus scan combines signature matching, heuristic analysis, and real-time behavioral monitoring to catch both known threats and new malware that has not yet been catalogued.

You should run an antivirus scan in several situations:

Routine maintenance. Running a full scan once a week is a reasonable habit for most Windows users. Real-time protection catches most threats as they arrive, but a scheduled full scan can surface anything that slipped through.

After downloading software. Any time you install software from outside the Microsoft Store or a trusted publisher, running a scan immediately afterward is a sensible precaution.

After opening a suspicious email attachment. Phishing emails frequently carry malicious attachments. If you opened something you are not sure about, scan your PC right away.

After connecting an external drive. USB drives and external hard drives can carry malware from other systems. Scan any removable media before opening files from it.

When your PC is behaving strangely. Unexplained slowdowns, browser redirects, unexpected pop-ups, or programs launching on their own are all signs that a malware scan is overdue.

The exact steps depend on which antivirus software you use, but the general process is the same across most Windows security tools.

Using Windows Security (built-in):

1. Open the Start menu and search for Windows Security.
2. Click Virus & threat protection.
3. Under Current threats, click Quick scan — or click Scan options to choose a full scan or custom scan.
4. Wait for the scan to complete and review any findings.

Using SentinelForge Security:

1. Open the SentinelForge Security dashboard from the system tray or Start menu.
2. Click Scan in the left navigation panel.
3. Choose Quick Scan, Full System Scan, or Custom Scan depending on your needs.
4. Review the scan results and follow the recommended actions for any detected threats.

You can also schedule automatic scans so your PC is checked regularly without manual intervention.

Most antivirus software offers at least two scan types. Understanding the difference helps you choose the right one for the situation.

Quick scan checks the locations where malware most commonly hides — startup entries, running processes, system memory, and common infection points in the Windows registry and file system. A quick scan typically takes 5 to 15 minutes and is suitable for routine checks.

Full scan examines every file on every drive connected to your PC. This is thorough but time-consuming — a full scan can take anywhere from 30 minutes to several hours depending on how much data you have stored. Run a full scan when you suspect an infection, after a security incident, or as part of a periodic deep-check routine.

Custom scan lets you target a specific folder, drive, or file. This is useful when you want to check a specific download or external drive without scanning your entire system.

Scan duration depends on the scan type and the amount of data on your PC.

• Quick scan: 5–15 minutes for most systems
• Full scan: 30 minutes to 3+ hours depending on storage size and file count
• Custom scan: Varies based on what you are scanning

Modern antivirus software is designed to minimize performance impact during scans. SentinelForge Security uses a lightweight scan engine that prioritizes active files and defers low-priority checks to idle time, so your PC stays responsive while a scan runs in the background.

When an antivirus scan detects a threat, the software takes one or more of the following actions:

Quarantine. The file is moved to an isolated area where it cannot run or interact with other files. This is the most common first response. Quarantined files are not deleted immediately — they are held so you can review them before deciding what to do.

Delete. Some threats are automatically deleted if they are clearly malicious and have no legitimate use. The software will typically notify you before permanent deletion.

Alert and recommend. For ambiguous detections, the software presents the finding and asks you to decide: quarantine, delete, or allow. If you recognize the flagged file as something you intentionally installed, you can mark it as trusted.

Block in real time. Real-time protection can help stop a threat before it executes — before a scan is even needed. This is the first line of defense, and it operates continuously in the background.

After any threat is found, it is worth reviewing what the malware was, how it got onto your system, and whether any other files may have been affected.

Real-time protection catches most threats automatically, but some infections are designed to be subtle. Watch for these warning signs:

• Unexplained slowdowns — your PC is significantly slower than usual with no obvious cause
• Browser redirects — your browser takes you to sites you did not navigate to
• Unfamiliar programs — software you do not recognize appears in your installed programs list or system tray
• Disabled security tools — your antivirus or Windows Security has been turned off without your input
• Unusual network activity — your internet connection is active even when you are not using it
• Pop-up warnings — fake security alerts urging you to call a phone number or download something
• Missing files — documents or files have disappeared or been renamed

Any of these symptoms warrants an immediate full scan. For more guidance on recognizing and responding to threats, visit the SentinelForge Security Center.

SentinelForge Security is Windows antivirus software built to go beyond basic signature scanning. It combines multiple detection layers to catch threats that simpler tools miss:

Real-time protection monitors file activity, process behavior, and network connections continuously — helping stop threats before they can execute.

Behavioral analysis watches how programs behave rather than just what they look like. A piece of malware that has never been seen before can still be caught if it starts acting like malware.

Cloud reputation intelligence cross-references files against a continuously updated threat database, so new threats are identified faster than signature updates alone allow.

Ransomware protection is designed to detect encryption behavior early, and protects shadow copies so recovery is possible even if an attack partially succeeds.

Malware removal covers the full spectrum of threats — viruses, trojans, spyware, adware, rootkits, keyloggers, and cryptominers — not just the most common categories.

SentinelForge Security is compatible with 64-bit Windows 10 and Windows 11. View pricing plans starting at $7.99/month.

Running regular antivirus scans is one of the most effective things you can do to keep your Windows PC secure. Pair scheduled scans with real-time protection and you cover both the threats that arrive in real time and anything that may have slipped through undetected.

Download SentinelForge Security and run your first antivirus scan today — or explore Windows antivirus plans to find the right level of protection for your home or business.

How often should I run an antivirus scan? For most users, running a full scan once a week is a good baseline. Real-time protection handles day-to-day threats automatically, but a weekly full scan catches anything that may have been missed. If you frequently download files or connect external drives, consider scanning more often.

Can antivirus detect malware? Yes. Antivirus software is specifically designed to detect malware — including viruses, trojans, spyware, ransomware, adware, rootkits, and keyloggers. Modern antivirus tools use multiple detection methods, including signature matching, behavioral analysis, and cloud reputation checks, to identify both known and previously unseen threats.

Should I use a quick scan or full scan? Use a quick scan for routine daily or weekly checks — it covers the most common infection points and takes only a few minutes. Use a full scan when you suspect an infection, after a security incident, or as part of a monthly deep-check routine. A full scan examines every file on your system and takes longer but is more thorough.

Can a virus hide from an antivirus scan? Some advanced malware is designed to evade detection — for example, by disguising itself as a legitimate system process or by disabling security software. This is why behavioral analysis matters: even if a threat does not match a known signature, unusual behavior can still trigger a detection. Keeping your antivirus software and Windows updated reduces the window of exposure to new evasion techniques.

What should I do if antivirus finds a threat? Follow the software's recommended action — usually quarantine or delete. After removing the threat, run a second full scan to confirm nothing else was missed. Review how the threat got onto your system (a suspicious download, email attachment, or external drive) and take steps to avoid the same vector in the future.

Do Windows computers need antivirus protection? Yes. Windows is the most widely targeted operating system for malware, and while Windows 11 includes Microsoft Defender as a baseline, dedicated antivirus software provides deeper behavioral analysis, better incident forensics, and more comprehensive protection against advanced threats like ransomware and rootkits.