Ease of Use
Exceptional antivirus software is simple to use, regardless of a user's computer experience or knowledge of viruses. The software should be easy to install and configure. If you need to use the interface to change settings, it should be intuitive and non-threatening to beginners. Ideally, most features will be enable/disable toggles with the power to fine-tune if desired. The best antivirus software is the kind you simply install on your system and then let it do its work.

Effective at Identifying Viruses and Worms
The best antivirus software identifies infected files quickly through realtime scanning, searching for viruses in a multitude of sources, including email, instant message applications, web browsing, etc. Scanning speed is also important. Slow antivirus software will tend to interfere with your work or gaming, and if it’s very slow or you are particularly impatient, you might have the tendency to stop or pause the scan, rendering the software useless. Generally, antivirus software scans your hard drive and files looking for known viruses.

Effective at Cleaning or Isolating Infected Files
Truly capable antivirus software thoroughly cleans, deletes or quarantines infected files, keeping them from spreading throughout the hard drive or network. Proactive/heuristic testing enables the antivirus software to detect and quarantine code that looks and acts like a virus even before it has been reported. This could be critical in protecting you on a “Day Zero” attack and spare you from being one of the first casualties.

Activity Reporting
Antivirus programs should give immediate notification of viruses found by realtime scanners and should provide an easy to read report of scan results, including what was found and what was done with infected files.

Feature Set
A well-rounded feature set allows antivirus software to provide absolute protection. The best programs are those that offer a wide variety of tools, from basic realtime scanning to more advanced heuristic scanning and script blocking. When it comes to virus protection, the more options the better. Many of the best antivirus packages now include multiple protection schemes at no extra cost. These include antispyware, antimalware, rootkit detection, parental controls and email screening, as many of the new threats are not literally viruses, but rather a variety of malware.

Ease of Installation and Setup
Antivirus programs should be a breeze to install, making it easy to go from installation to initial scan in just a couple clicks of the mouse.

Help Documentation
High-end antivirus software comes with plenty of help, including support via email, online chat or via telephone. There should also be online resources, such as knowledge bases and FAQs available for quick and convenient help.