It is designed for Windows PC, using the smallest resource footprint possible to provide complete anti-malware protection and will include a new protection technology, as part of the Microsoft anti-malware engine, called Dynamic Signature Service.
If you are not currently running any anti-malware software on your computer then you may be vulnerable to spyware, viruses, and other malicious software, you may get to see Microsoft Security Essentials, being offered under a separate heading ‘Security Essentials Free Antivirus‘ as an 8 MB download.
Microsoft Security Essentials is a free anti-malware software and it is strongly recommended that you download and install it. It is licensed for use on home PCs and by small businesses with 10 or fewer PCs.
For more visit Microsoft KB2267621.