The function keys have been replaced by the Touch Bar
As was rumored, the most noticeable change has been made to the top part of the keyboard, which now features an OLED panel that changes based on what you're doing on the screen. The functions shift based on the app you're using -- for instance, if you're in Safari, it displays icons of your favorite web pages for quick access. In iMessage, you can easily browse and select emoji, and it makes it incredibly easy to format your text while composing messages in Mail. It also toggles back to the basic functions whenever you want -- so you can still easily change the volume or brightness. The panel also supports multi-touch input, which means editing in programs like Final Cut Pro and Photoshop is now easier and more intuitive.
Additionally, the upper right corner is equipped with Touch ID, meaning you'll be able to use your finger print to buy stuff from sites that support Apple Pay, and quickly sign in to, or switch between, user accounts if you share a machine.