OS X 10.9, better known as Mavericks, is the 10th iteration of the operating system that powers Apple's desktops and laptops. Unlike previous versions, Mavericks is the first to be named after a place in California instead of a large cat -- and the first to be given away by Apple for free. Even so, it still looks and acts very much like its predecessor, Mountain Lion, meaning there's no major learning curve for users who upgrade.
Like iOS 7, Apple's just-updated mobile OS, Mavericks has been stripped of skeuomorphic elements. Unlike iOS 7, the overall user interface has been left largely intact. Instead, Mavericks is focused on refinements throughout the operating system and built-in apps, a few invisible features largely designed to improve laptop battery life and a couple of big additions borrowed from iOS.
Before you install Mavericks, be sure to back up your Mac. In fact, it wouldn't hurt to do a scan of your system using Disk Utility (it's in the Applications > Utilities folder) or with a third-party utility like Disk Warrior, just in case things aren't running as well as they should be. Thousands of files are about to be swapped around your hard drive as you upgrade to Mavericks, so it makes sense to make sure everything is in tip-top condition.
Mavericks is available through Apple's Mac App Store (which can be found under the Apple Menu). Open the App Store and, if Mavericks isn't in the Featured area, click on Updates. OS X Mavericks should be at the top of the list of software you can download and install. Note: You can install Mavericks on any Mac that's authorized with the Apple ID you're using. And it has the same hardware requirements as any Mac that can run Mountain Lion. (You do need to be running at least OS X 10.6.8 -- Snow Leopard -- to upgrade to Mavericks.)
The Installer downloads to your main Applications folder, so if you're strapped for bandwidth and have multiple machines -- or even if you just want to keep a copy of the installer on your computer -- make sure to drag the installer out of the Applications folder before you begin the update. (You need to hold down the Command key when you drag the installer to a different location.) If you don't move it to a different location, the installer will delete itself after the upgrade.
Installation on my 2012 MacBook Pro (Retina) took just under 35 minutes, and the process is simple. Double-click the Installer, enter your username and password, select your target destination -- for most users this is the Macintosh HD -- and the installer does the rest, even rebooting itself when needed.
After the installation, a setup assistant will prompt you to log into iCloud and set up iCloud Keychain. This brings us to our first new feature.
iCloud Keychain is what your keychain is for your keys -- for passwords. iCloud Keychain is a single place to store your username and passwords for all types of applications, network shares, disk images and websites. This is nothing new to Keychain users -- this technology has been included on every Mac dating back to 1999's Mac OS 8.6. What's new is the addition of iCloud support, which keeps all authorized computers (and, eventually, iOS devices) up to date with the latest password data, which is stored in a 256-bit AES encrypted file. When you're prompted for a username and password by a network share or Internet site, Keychain automatically fills in the information so you don't have to.
Security experts always advise users to create a unique password for every account, but few people do that. iCloud Keychain could help change those bad habits with a built-in password creator that can be used when setting up a new account. It generates a random series of numbers and letters, producing a password that would be tough to guess (and maybe tougher to remember). But Keychain remembers it for you, and passes that data to your other devices. So the next time you log into a site on any device you own -- including a mobile device like an iPhone -- the username and password is remembered by Keychain via iCloud and entered automatically.
Keychain also remembers credit card data -- if you allow it to -- so you don't have to keep pulling out your credit card and manually entering data when doing online purchases. (For security's sake, you're still required to fill in the 3-digit security code located on the back of the card.)
Knowing what iCloud Keychain is, you can make an informed decision during the initial setup about whether to use it. You can either activate it now or leave it for later. If you do use iCloud Keychain, it will require you to verify who you are. One way that's done is by sending notifications to your other devices, so you can confirm that you are, indeed, the owner of the Apple ID account you're signed in with; the alternative is to send an SMS message to the phone number listed in your Apple ID. (Once you get the SMS, you input the code into a dialog box in Mavericks.)