Apple has released OS X Mavericks for OS X and it is a free update to all users. This update will work on any computer made after 2007 but you need to be running Snow Leopard or later to do so. Head over to the source link to download the update for your computer. You should be safe as far as files and data go although you can never be too sure, I recommend having a backup just in case.
With OS X Mavericks, the Mac experience gets even better. It brings new apps to your desktop. Adds features you’ll love to use. And introduces technologies that help your Mac perform even better — while using even less power.
With more than 200 new features, OS X Mavericks brings Maps and iBooks to the Mac, introduces Finder Tabs and Tags, enhances multidisplay support, and includes an all-new version of Safari. The latest release of the world’s most advanced desktop operating system also adds new core technologies that deliver breakthrough power efficiency and responsiveness.
Source: App Store