This question is asked over and over again.
Apple/Mac and Android users – I recommend Bit-Defender for both systems. (see link below)
Window 10 comes with Windows Defender already installed. I also recommend Malwarebytes as a secondary check for Adware and other forms of Malware that Windows Defender does not check.
Older versions of Windows require an anti-virus program and I recommend AVG or AVAST as well as Malwarebytes. There are Free Versions available.
The Best Protection is YOU! Practice safe prodedures when surfing the Internet. Read recommended Security Tips
AVAST OR AVG Recommended for Windows 7
Bit-DefenderRecommended for Mac, Android and Windows
MalwarebytesStrongly Recommended for Windows (all versions)
It is not recommended to have two anti-virus programs installed at the same time. They will conflict with each other. Malwarebytes is an exception, and works well with other programs.
On-Line Virus Scan
This page last updated: 6 Jan 2019