Improved Data ProtectionMacOS Catalina makes apps jump through more hoops—as in, forcing them to ask for permission —if they want to access the parts of your computer where documents and other personal files are kept. That includes iCloud Drive and external drives, for example.
Another change, which isn't as visible to end users, is that macOS itself is now being stored on a separate disk volume. In other words, it's isolated from the rest of your data and programs, so apps won't be able to mess with important system files; they simply won't have access to them.
Weak Password WarningsSafari on both macOS and iOS has been pushing better password security for a while now, but with Catalina's arrival, the desktop browser will actively warn you if you sign into a site with a weak password—one that's short and simple enough to be easily cracked.
When this happens, you'll be prompted to change your password to something stronger, though you can ignore the advice. When you sign up on a new site, meanwhile, Safari recommends a new, strong password for you that it'll then remember.
To see all of your passwords, and to see which ones Safari has detected as weak or duplicated, open Preferences from the Safari menu and choose Passwords.
Sender-Block in MailYou no longer have to put up with emails from unwanted contacts, because Mail in macOS Catalina has been upgraded to let you block senders. With an email open, click the arrow next to the sender name, then choose Block Contact. All future emails from that individual will go straight to the Trash folder.To see a list of all the senders you've blocked, and to unblock them if you're feeling charitable, go to Mail > Preferences > Junk Mail > Blocked. You can add email addresses to your block list manually here, too.
Better Screen Time LimitsWith macOS Catalina, Screen Time makes it to the Mac—that means as well as seeing just how much time you spend on Netflix each day, you can also keep your kids safe on a Mac by putting limits on their usage, with these configurations protected with a passcode you specify.Open up Screen Time via System Preferences from the Apple menu on macOS. The tool lets you put time limits on access to certain apps or websites, and to restrict the viewing of adult content, both on the web and with music and video purchases from Apple. It doesn't just limit the hours your kids spend the computer, but helps you to keep tabs on what they're doing when they are.
Enhanced Gatekeeper Technology
One of the biggest under-the-hood security upgrades in macOS Catalina is to the Gatekeeper component of the operating system—basically the part of macOS that's in charge of keeping viruses and malware off your system. It's now harder than ever for malicious software to do damage to a Mac computer.In particular, any software installed outside of the Apple-approved walled garden that is the Mac App Store is now checked every time runs for malware and other problems. Previously, this would only happen the first time the app launched. Code from these apps must also be submitted to Apple by developers to be pre-approved as safe, a process known as notarization.