macOS X 10.11 El Capitan was released on September 30, 2015. Similar to macOS X 10.6 Snow Leopard, Apple described this release as emphasizing "refinements to the Mac experience" and "improvements to system performance". Refinements include public transport built into the Maps application, GUI improvements to the Notes application, adopting San Francisco as the system font for clearer legibility, and the introduction of System Integrity Protection.
The Metal API, first introduced in iOS 8, was also included in this operating system for "all Macs since 2012". According to Apple, Metal accelerates system-level rendering by up to 50 percent, resulting in faster graphics performance for everyday apps. Metal also delivers up to 10 times faster draw call performance for more fluid experience in games and pro apps.
If you own a Mac released since 2009, you should be able to install or update to El Capitan. Check Apple’s website for minimum requirements if you aren’t sure, but with 2GB of RAM, 8GB of storage space and a 64-bit CPU needed, pretty much any Mac desktop or laptop dating back to 2007 is supported. If updating, the Mac to be updated must also be running at least macOS X 10.6.8 (Snow Leopard).