Expand is a tool built for those who read broadly, lookup words frequently, and have observed frustratingly how the meanings of less-common words fade from the mind in time. It doesn't provide a "word of the day" or any of the other fluff focused on by most vocab apps. Expand lets you look up words quickly, collect the ones that you have reason to retain, and review them using a method of spaced repetition in order to do so most efficiently. If you're the kind of person who looks up the meaning of words frequently, then this app is being built and continuing to be improved for you.