Water and consumer electronics generally don't mix. In most cases, you'd want to keep your smartphones and tablets, your game consoles, your controllers, remotes, etc. away from any sort of water source for the most obvious reason that the water could damage your electronics. Water also makes it hard to use the touchscreen on a device like a smartphone or tablet, unless you're using something like the Sony Xperia Z4 tablet powered by the Qualcomm Snapdragon 810 which utilizes Qualcomm's improve Touch technology. Sony devices are known for being waterproof and the Xperia Z4 tablet can certainly withstand a little moisture. Thanks to Qualcomm's improve Touch tech though you can also continue using it even if the screen gets wet.
Qualcomm makes this work with a feature called advanced water rejection which was specifically designed to eliminate the possibility of false responses from water on the screen. When water hits the display on a device without this technology, the water is going to register as a finger touch and the screen will have difficulty telling the difference between the beads of water and your fingers. Qualcomm's improve Touch with advanced water rejection in the Sony Xperia Z4 Tablet is built to combat this type of issue so users can continue actually using their device even if the screen gets wet.
In the video below where Qualcomm demos this technology working, you can see how well the tablet continues functioning even after it gets sprayed with water multiple times. The responsiveness is nearly unchanged compared to the first tablet which isn't usable at all after getting wet. Qualcomm states that the technology was designed to track multiple finger touches even when wet, so they thought specifically about these types of conditions to make sure things could still work. Most people probably aren't planning on using their tablets in the rain on a daily basis, but knowing your tablet can work even if you happen to get caught out in the rain can bring some peace of mind. Paired together with the Qualcomm improve Touch technology, Sony's waterproofing on the Xperia Z4 tablet makes it easy for people to stop worrying about wet screens.