The Air View feature of the Samsung Galaxy S4 lets you hover your finger over the screen, without touching it, to interact with the display. You can preview emails and images, all without actually having to touch the screen.
With Air View you can quickly view files and emails on your phone in a preview so you don't have to open them fully, saving time. So, if you're looking for a particular email in a long chain of emails, just hover over one and the preview of the contents will pop up. Not the right one? Try another, you'll save time by not having to open up the email. Not sure which photo is the right one? Hover over it for a close up. It works with videos too, so if you want to watch a certain video, hover it with your finger and you'll get a preview.
Just select the Air View option from the Settings menu and you'll be able to start Air Viewing on your S4. Just hover your finger over the section of the screen with the file you want to preview and a small box will pop up. The screen itself works like any other screen – it recognises your finger by conductivity. It's just that the Galaxy S4's screen is super sensitive and can detect your finger from further away than most other screens. In fact, it's so sensitive you can use gloves on the screen as it can sense your fingers through the fabric.