Summary
There are a host of nasty intruders on the Internet including viruses, trojans, worms and spyware. Microsoft Security Essentials offers award-winning protection against these intruders without getting in your way.
Downloading and installing Microsoft Security Essentials is free and easy. Once you have installed it, the software updates automatically once a day. We’re constantly tracking new threats and we keep your PC updated to help protect you. You don’t have to do anything. Microsoft Security Essentials uses green, yellow and red color codes to designate the security status of your PC and a color-coded icon in the taskbar tells you at a glance if your attention is needed. It’s simple—when you’re green, you’re good. However, if there’s a red or yellow threat, Microsoft Security Essentials will alert you and recommend what to do (you can act directly from the notification area without having to enter the application).
Microsoft Security Essentials runs quietly in the background. You’ll only be alerted when there are specific actions to take. When you’re away or busy, Microsoft Security Essentials can take the default action on your behalf and you can open the program later to review and undo those actions if you wish.
Microsoft Security Essentials is efficient and compact. Scans and updates are scheduled to run when the PC is idle and the software works in a way that your PC is still snappy when you’re using it. All this makes Microsoft Security Essentials friendly for all sorts of computers—your old PC, your new PC, your laptop, as well as your little netbook.
Got Windows 8 or Windows RT? Windows Defender for Windows 8 and Windows RT provides the same level of protection against malware as Microsoft Security Essentials. You can't use Microsoft Security Essentials with Windows 8, but you don't need to — Windows Defender is already included and ready to go. But if you’re looking to protect a PC with an older version of Windows, you can use Microsoft Security Essentials to help guard against viruses, spyware, and other malicious software. It provides real-time protection for your home or small business PCs.
More Information
http://windows.microsoft.com/en-GB/windows/security-essentials-product-information#tabs1=overview
