Every year, I write hundreds of Mac 911 columns for Macworld, and read thousands of emails from readers sent that account and directly to me. Consistent themes emerge, and many center around how to use one’s Mac safely. Apple has kept Macs effectively entirely free of widespread malware. While some ne’er-do-wells have infected limited numbers of Macs, and some state agents around the world have used unpatched exploits to attack individuals, most of our biggest concern is securing our data against unwanted access, rather than blocking huge masses of malware.

That’s informed my latest book, Take Control of Securing Your Mac. The biggest threats to your Mac are from apps you install that don’t properly disclose their intent, phishing and other email- and web-based attempts to convince you to do things you shouldn’t, and physical access, in which someone gets ahold of your Mac in your home or office or steals it and extracts data. Apple has also made an increasingly number of changes across the last three releases of macOS—Mojave, Catalina, and Big Sur—that this book covers that make it nearly impossible for bad actors to corrupt system files, even if they managed to hijack a user account with administrator privileges.