All testing was carried out by respected antivirus testing lab AV-Test in Germany. Each internet security suite was installed on a PC running Windows 7 Ultimate with Service Pack 1, using default settings.
The PC's web browser was then directed at 19 URLs known to contain malware. AV-Test monitored the system to find out if the malware was completely blocked, not completely blocked (but some damage was prevented) or not blocked at all (the system got infected).
AV-Test also ranked how well each suite dealt with different types of malware such as bots, viruses, worms, password stealers, downloaders, rogue apps (such as fake AV) and potentially unwanted applications.
As with any antivirus testing, each suite was also ranked for the number of false positives - such as when a file was reported as being malware when it was, in fact, not.
A barrage of performance tests were also carried out, from startup and shutdown times to installing and running several common applications. The average download time of files from four websites was measured, as was the average page loading times from 20 popular websites. In each case, the tests were run seven times to get an average figure.
The top five 2013 internet security suites in our tests were F-Secure Internet Security 2013, Norton Internet Security, Trend Micro Titanium Internet Security 2013, Bitdefender Internet Security 2013 and Kaspersky Internet Security 2013 (click the links to read our full reviews or see our security software reviews.)