Touchwiz is Samsung's custom skin over Android. IT's features are:
. Eye tracking features have been extended on the S4; the new "Smart Scroll" feature can be used to scroll while looking at the screen by slightly tilting the phone, and "Smart Pause" allows the video player to pause videos if the user is not looking at the screen. "Air View" implements gestures and other functionality (such as previewing images or messages) by holding or swiping a hand or finger slightly above the screen. The "Group Play" feature allows ad hoc sharing of files between Galaxy phones, along with multiplayer games and music streaming between Galaxy S4 phones. The "Adapt Sound" and "Adapt Display" functions can automatically adjust settings for the screen and sound system for optimal quality.[citation needed]
The camera app implements numerous new features (some of which were first seen on the Galaxy Camera), including an updated interface, and new modes such as "Drama" (which composes a moving element from multiple shots into a single photo), "Eraser" (which takes multiple shots and allows the user to remove unnecessary elements from a picture), "Dual Shot" (which uses the front-facing camera for a picture-in-picture effect), "Sound and Shot" (which allows the user to record a voice clip alongside a photo), "Animated Photo", and "Story Album" among others. Other new pre-loaded apps include WatchOn (an electronic program guide that can utilize an infrared transmitter on the top of the phone as a TV remote), S Translator, the workout tracker S Health, S Voice Drive, S Travel, and an optical character recognition app. A new enterprise-oriented feature known as Samsung KNOX allows the phone to be separated into modes for personal use and business use, and gives the business mode high security.[12] It supports the aptX codec which improves Bluetooth-headset connectivity
It's really that long.