Quizlet is used almost daily by 12 million people but you’ve never heard of it unless you have a high school student. It’s a cloud-based flash card app.
Quizlet works for whatever you want to study and I am investigating to look at for one of my classes. It is easy and fast to add a card. No paper, auto-define buttons, lots of keyboard shortcuts make the process of creating a Quizlet quick and painless. Because Quizlets are all stored in the cloud, they can be accessed from anywhere. There’s built in gamification and a lot of other features which I just starting to try and it is completely free.