Avast Antivirus products are divided into various levels. It is a reliable and high-performing program. In third-party testing metrics, it routinely ranks in the top three. Most users will be satisfied with the free version which you can download from Avast.com/setup login. If you visit shady websites frequently, you should upgrade to the premium version. There is also a version for businesses. All of them function flawlessly and consume very little system resources. Avast just acquired its competitor AVG, which was a great product as well. Avast has been installed on over 200 computers in my organization.