This app of the day is one of the most popular apps, at the time of this article. What's the Word? is a simple game to learn and can be highly addicting. The game shows you different, apparently random, pictures that have a single word in common. You have to think outside of the box and find the word that can be used to describe all four pictures. There are dozens of unique picture puzzles to solve. It may sound easy, but it gets harder the farther you go along. What' the Word? is free for the iPhone, iPad and Android phones.