OS X Mavericks is available today for free from the Mac App Store. Any Mac capable of running OS X Mountain Lion can also run Mavericks. You can upgrade to Mavericks for free directly from OS X Snow Leopard, Lion or Mountain Lion. For a complete list of system requirements and compatible systems, please visit Apple.
With more than 200 new features, OS X Mavericks brings iBooks and Maps to the Mac, includes a new version of Safari, enhances multi-display support, introduces Finder Tabs and Tags, and delivers new core technologies for breakthrough power efficiency and performance. Timer Coalescing and App Nap intelligently save energy and reduce power consumption. Compressed Memory automatically shrinks inactive data to keep your Mac fast and responsive. Mavericks also delivers significant performance enhancements for systems with integrated graphics through optimized OpenCL support and dynamic video memory allocation.