Learn how to get a free antivirus scanner for Microsoft Windows. Learn how to protect your computer from viruses using Microsoft Security Essentials. Microsoft Security Essentials works with Microsoft Windows XP, Windows Vista and Windows 7. Microsoft Security Essentials is available for free those that have a verified copy of genuine Windows. No registration or personal information is required, only automatic verification of your genuine Windows installation.

What is a virus scanner?

Virus scanner is software that is used to detect, prevent and remove malicious software. Malicious software is also known as malware (short form for malicious software). Malware can be in many different forms. Malware comes in the form of computer viruses, worms and Trojan Horses. Some antivirus software can also detect adware and spyware.

What is a computer virus?

It can range in as causing simple pranks, maliciously deleting data on computers and even allowing backdoor to your computer systems. What computer virus do:

  • Cause your computer system to perform poorly
  • Change your web browser's homepage
  • Prevent applications from running properly or not run at all
  • Delete files from your computer system
  • Execute programs running in the background without your knowledge
  • Allow hackers to remotely control your computer, giving the hackers full access to your computer system
  • Infect and corrupt files on the computer system
  • Replicate itself and spread within the computer or to other computers on private and public networks, internet

How does one get infected?

To get infected, usually you will have to execute/run malware.

  • Web Browsing
    • When visiting web sites, you may be prompted with a message stating a unique plug-in is required. Without understanding what the plug-in is, you accept. In doing so, you had allowed that program to run/execute.
    • Always pay attention to what plug-ins you are accepting. It is best that you only install plug-ins from reputable companies. If you want to install Adobe Flash Player, then get it from Adobe's website.
  • Opening/running e-mail attachments
    • You receive an email containing an attachment containing the malware. You open the attachment. If the attachment was an executable, then you had just allowed that program to run/execute.
    • You should never open attachments from unknown senders.
    • Be careful of spoofed e-mails. Spoofed emails are emails that appear to be from legit company but in fact the sender e-mails are spoofed (faked).
  • Installing pirated/downloaded software, movies and/or music files
    • Never install pirated software, music and movies. Not only is it not ethical, some of these may actually be virus (or Trojan Horses) disguised as software, movies and/or music files.

Why do you need an antivirus scanner?

  1. There are really two purposes for antivirus software. It is use to prevent malware from infecting your computer by detecting and quarantining the malware before the malware has the chance to infect your computer (before you execute/run the malware).
  2. The second is to try and remove already infected files and systems.

How do antivirus scanners work?

The virus scanner will scan your computer for virus and will quarantine, clean and/or delete infected files. There are generally 2 types of scans.

  • Scheduled Scans
    • These are scans that are scheduled to run on a predetermined date/time. It will typically scan all fixed drives.
  • Real Time Protection
    • These are scans that occur in real time.
      • When an infected file or malware is downloaded from the internet, the virus scanner will alert you and prompt you to quarantine, clean and/or delete.
      • When you receive an attachment in an email, the real time scan can detect if the attachment is a malware.
      • When you are copying files from a USB key or another computer from the network, the real time protection scan can detect if the file is a malware.

If real time protection can detect virus in "real time", why do I need to scheduled scans? This is a very good question. Real time protection scan works at the time a file is first known on your computer. If at that time, a new virus was created but is unknown (not in the virus definition) to the virus scanner, it will go undetected.

As new viruses are created daily, your antivirus scanning software need to know of these new viruses. This is where virus definitions come in. The virus definition list is an updated list of new virus and how the scanner detects and removes the viruses. Your antivirus scanning software will periodically update its virus definition for you (assuming you have internet access).

Generally the antivirus scanner will scan all files and directory from your hard drives. While scanning files, these files may be locked. This means that no other application can write to the file when it is being scanned. There are some files that don't need and shouldn't be scanned. Here is a quick list of the files that don't need to be scanned: *.hst, *.log, and *.txt. How do I tell the virus scanner not to scan these file types? Antivirus scanners have something called "Exclusion List". This exclusion list tells the virus scanner not to scan files and file paths with the exclusion lists.

Where can I get a free antivirus scanner?

There are several companies that build antivirus scanner software. Here is a list of the popular antivirus software: McAfee AntiVirus, Symantec Security Scan, Norton AntiVirus, Trend Micro Internet Security Pro, AVG Internet Security and Kaspersky File Scanner. Some of these companies offers free basic version of antivirus scanner software while the full version will need to be purchased. For full version of antivirus scanner, you generally will need to annually renew your antivirus scanner software. The renewal consists of software updates, patch updates and virus definition updates.

Microsoft had gone into the personal antivirus scanning software. Their antivirus scanner is called Microsoft Security Essentials. As long as you have a genuine Windows operating system, you can get Microsoft Security Essentials for free. Microsoft Security Essentials works with genuine Windows XP (Service Pack 2 or Service 3), Windows Vista (Service Pack 1 or Service Pack 2) and Windows 7. In case you are wondering, yes Microsoft Security Essentials also supports Windows XP Mode in Windows 7. Microsoft Security Essentials is a full version download. It is easy to install and use. Why buy antivirus software if you can get one from Microsoft for free? You can download it at Microsoft Security Essentials' site.

For more computer security tips, read the article learn how to How to create a strong password.