English, Bulgarian, Chinese (Simplified), Chinese (Traditional), Croatian, Czech, Danish, Dutch, Estonian, Finnish, French, German, Greek, Hungarian, Italian, Japanese, Korean, Latvian, Lithuanian, Norwegian, Polish, Portuguese (Brazilian), Portuguese (Portugal), Romanian, Russian, Serbian (Latin), Slovak, Spanish, Swedish, Thai, Turkish, Ukrainian and Vietnamese Microsoft Security Essentials (MSE) is an antivirus software (AV) product that provides protection against different types of malicious software such as computer viruses, spyware, rootkits and Trojan horses.

microsoft security essentials not updating xp-85microsoft security essentials not updating xp-12microsoft security essentials not updating xp-15

According to a March 2012 report by anti-malware specialist OPSWAT, MSE was the most popular AV product in North America and the second most popular in the world, which has resulted in the appearance of several rogue antivirus programs that try to impersonate it.

Microsoft Security Essentials is an antivirus software (AV) product that fights malicious software (malware), including computer viruses, spyware, Trojan horses and rootkits.

It replaces Windows Live One Care, a discontinued commercial subscription-based AV service, and the free Windows Defender, which until Windows 8 only protected users from adware and spyware.

The product received generally positive reviews praising its user interface, low resource usage and freeware license.

It secured AV-TEST certification on October 2009, having demonstrated its ability to eliminate all widely encountered malware.

However, it lost the certificate on October 2012, having shown a constant decline in protection and repair scores.

In June 2013, MSE achieved the lowest possible protection score, zero.

It lacks the personal firewall of One Care or the centralized management features of Forefront Endpoint Protection.

Microsoft's announcement of its own AV software on 18 November 2008 was met with mixed reactions from the AV industry.

Symantec, Mc Afee and Kaspersky Lab—three competing independent software vendors—dismissed it as an unworthy competitor, but AVG Technologies and Avast Software appreciated its potential to expand the consumers' choice of AV software.

AVG, Mc Afee, Sophos and Trend Micro claimed that the integration of the product into Microsoft Windows would be a violation of competition law.