Preview at WWDC likely in June, followed by September launch.
Apple Releases OS X 10.11.6 El Capitan With Bug Fixes and Security Enhancements
The OS X 10.11.6 update can be downloaded through the Software Update mechanism in the Mac App Store. It is available to all OS X El Capitan users.
Many of the updates to the El Capitan operating system have focused primarily on under-the-hood improvements, bug fixes, and security enhancements instead of outward-facing changes, and OS X 10.11.6 continues that trend.
OS X El Capitan will be followed by macOS Sierra, the next-generation Mac operating system that Apple announced at the 2016 Worldwide Developers Conference. macOS Sierra includes features like Siri integration, storage optimization, Photos improvements, auto unlocking with the Apple Watch, cross-device copy and paste, and more.