When a threat or problem is detected, MSE automatically blocks it and alerts the user. MSE can also be used to perform manual scans of files, folders or an entire PC for viruses, worms, Trojans, spyware and other malware. MSE is free for home use or for small businesses with up to 10 PCs.
Version 4.5 of Microsoft Security Essentials, which entered the beta stage in February 2014, will not support Windows XP. MSE is not compatible with Windows 8, which has its own antimalware program called Windows Defender.