If you are running a windows OS on your computer then you must require an antivirus for protection from various threats. There are many antivirus softwares available in the market which you can use. Of course most of them are paid ones but you can get it free for one year as Avast Antivirus License for 1 year absolutely free is offered on their website.
All you need to do is goto this link and fill out the details. You will have your license key delivered to your email within 30 secs. Around one and half years back they started this offer and it is still valid.
Avast is a good antivirus which provides great protections from various threats and does not slows down your system. So just give it a try and grab your license now by clicking here.