Apple senior vice president of Software Engineering Craig Federighi introduces the Yosemite operating system during the Apple Worldwide Developers Conference.

Spotlight also gets an overhaul, with a large front-and-center search interface.

The Safari browser also gets a more-streamlined look, with all navigation squished into a slim, uncluttered row.

The Notification Center will now have a more iOS-like look and feel, with translucent black panes and alerts from installed apps.

By placing files in an iCloud Drive folder, it now syncs and makes them accessible via all your devices.

To work around bounce-backs when you try to email big files to friends, Apple introduced a Mail feature dubbed Mail Drop.

Apple also showcased some proximity-based Continuity features aimed at easing the interaction between a user's iOS and OS X devices.

Also part of the Continuity package is a new feature that lets you tether your iPhone to your Mac wirelessly, answering calls and SMSes even when your phone is charging in the bedroom.

Also new: Handoff. A Mac can now recognize that you've started an email on an iPhone and allows you to finish it on your computer.

For developers, Yosemite is available right away. The public can sign up to join an open beta trial. The final version ships this fall for free.