What is a Virus and Using Windows Defender

Computer viruses are software applications that are designed to perform malicious actions, such as destroying or corrupting data. Most viruses are obtained by sharing and copying infected software. A virus can also be acquired by downloading infected files from the Internet. Although it may not have been intentionally downloaded, a virus or malware can find its way onto your computer from a variety of sources. Simple sources, such as a banner ad on a site you frequent, to the more devious, hidden downloads that sneak their way through the software you are installing.


Microsoft Security Essentials (MSE) was discontinued in January of 2020 along with Windows 7. ITS now recommends using Windows Defender that comes installed on all Windows 10/11 devices.

Intended Audience

This article is for the benefit of the faculty, staff, and students who would like to know more about computer viruses and the use of Windows Defender.


To follow this article you need a computer running Windows 10/11, a computer account with administrator rights, and to uninstall any previously installed anti-virus programs (see next section for help on this).

Preparation for Windows Defender

Before starting the install, make sure you have no other anti-virus program installed, be it full, free, or trial versions. If you have more than one anti-virus program installed, they might conflict with each other, working against you, rather than for you. To check if you have any other anti-virus programs installed, and if needed, to uninstall them, follow the steps numbered below:

  1. Click the Start button. (If you cannot find Control Panel, you may need to search for it first)
  2. Click Control Panel.
  3. If in the Large/Small icon view, click Programs and Features
    • If in Category view, under Programs click Uninstall a program.
  4. Select the old anti-virus program and click Uninstall at the top.

Downloading/Installing Windows Defender

Since Windows Defender already comes on Windows 10/11 devices, you will not need to download or install any additional software as it is built into Windows.

Scanning with Windows Defender

  1. Click the Start button and search in the start menu for Windows Security. You can also navigate to the Settings app, click on Update and Security, Click on Windows Security on the left, then Open Windows Security.
  2. Click on Virus & threat protection.
  3. Select Quick Scan or click on Scan options and select Full Scan and Scan Now.
    • Note: Quick Scan analyzes the most common areas a virus might hide and takes significantly less time. Full Scan analyzes the entire hard drive and can take many hours depending on the capacity and fullness of the hard drive and speed of the computer hardware. Only choose the Custom option if you want to scan a certain drive, folder, or group of locations, such as checking if there is a virus on your flash drive or external hard drive.
  4. Windows Defender will now begin a scan of your computer.
  5. Once the scan is complete you will see any threats that have been identified as well as the last scan time, elapsed scan time, and how many files were scanned.
  6. To see the results of your scan click on Protection history.

Additional Information

For a list of recommended anti-virus and anti-malware programs, please see our article Protecting My Computer.


If you have any questions or experience any issues with this article, please visit or contact the ITS Helpdesk for assistance.


Location: 206 Murchie Science Building

Hours: go.umflint.edu/hours

Phone: (810) 762-3123

Email: flint.its.support@umich.edu

Print Article


Article ID: 6186
Mon 8/16/21 3:10 PM
Wed 5/29/24 3:47 PM