Virus and Malware
Malware is any kind of virus, spyware, adware etc. that is either malicious or unwanted. Malware can cause performance problems on your computer as well as contribute to the loss of important files and personal information including identity theft. It's recommended you have some sort of anti-virus software installed with your computer.
Here are some recommended security software options:
Microsoft Windows built-in Security features are automatically updated and free. This is a great baseline for security as long as you keep your Windows version up-to-date and enable automatic updates.
Anti-virus protection as well as other producs.
Anti-malware manual scanning program that is great for cleaning up an infected computer.