The second version of the Apple Watch operating system, watchOS 2, was announced today at WWDC. It comes with a lot of incremental updates for users, but as you might expect at Apple’s developer conference, most of the biggest new features are enhancements for app makers.

Those upgrades include the ability to run apps natively on the Watch, and access hardware features that were previously restricted to first-party Apple apps. That should speed things up as apps won’t have to constantly communicate with the iPhone to perform basic functions.

Developers will also have access to a bunch of additional sensors on the Watch, including the accelerometer, microphone, speaker and Taptic engine. With the accelerometer, Apple showed off how users will be able to measure a golf swing, while the microphone will allow them to send voice memos over apps like WeChat.

Custom “complications” — small pieces of information on the Watch face — are also coming. Developers can create complications for the Watch face that show important data, like flight delays or the charge on your electric vehicle. Those complications can also respond to the new “Time Travel” feature, which lets users rotate the Digital Crown to advance or rewind — showing an upcoming meeting or when a flight leaves, for example.

Users will be able to customize their Watch face with a personal photo. Or they can choose from a selection of timelapses that Apple created. The timelapses will show images of iconic locations, including London, New York City and Shanghai, that update based on time of day.

The Watch will also function better on your nightstand. When you charge up at night, the display rotates so you can read the time. Alarms activate the speaker so you can now use your watch as an alarm clock.

The developer beta is coming out today, with the public release available in the fall.