You share many files with Windows users. Macs can act as "carriers" for Windows viruses that don't hurt the Mac but could infect your friends' PCs.
A "digital bouncer" that ensures you only install apps from the App Store or "identified developers" verified by Apple. do you need to buy antivirus software for mac
A newer tool that performs background scans to find and remove active infections that may have slipped past initial checks. You share many files with Windows users