In the Index, “what’s new in Mavericks” gives you a pretty comprehensive listing. But here are the big-ticket items:
Finder tabs and tags. Now desktop windows can have tabs, just like a Web browser, thus cramming multiple views into a single window. And you can tag your files with as many color-coded keywords (“Back me up,” “Important,” “Smithers project”) as you want, making it easy to round them all up with a click.
New apps. iBooks (for reading digital books you buy from Apple) and Maps (for plotting trips and sending routes to your phone) are now Mac programs—but they synchronize with your iPhone or iPad.
Updated apps. Calendar has built-in travel times for your appointments. Safari uses less battery power and consolidates bookmarks, Reading List, and tweets that contain Web links into a single sidebar.
iCloud Keychain. This one’s rather huge: OS X can now memorize all your passwords (for Web sites and WiFi networks) and credit cards and then auto-fill them when you’re logging into a Web site or buying something. Best of all, they’re also synced across your other Macs, iPhone, and iPad, so you have almost nothing to remember.
Multiple monitors. Each screen has its own menu bar; the Dock moves to whichever screen you click. If you have an Apple TV, then your TV screen can act as a wireless second monitor.
Notification improvements. You know those little top-right bubbles that let you know about incoming messages? You can now delete or reply to an email message or a Messages text right in the notification bubble. When you wake your Mac, you see a summary of notifications that came in while you were out.
And if there are certain hours when you don’t want any notifications to interrupt or wake you, Do Not Disturb makes its debut on the Mac, too.
Offline dictation. You no longer need an Internet connection to use OS X’s “speak to type” feature.
Engineering improvements called things like App Nap, Timer Coalescing, and Compressed Memory are all designed to make your laptop’s battery charge last longer. Handy, since 75 percent of all Macs are laptops these days.