Describe an app you use frequently

The app I use most, apart from messaging, is a spaced-repetition flashcard app called Anki. I started using it about two years ago when I was preparing for an exam, and unlike most apps I've downloaded, I actually kept using it after the exam finished. I open it every day, usually on the bus in the morning — maybe fifteen minutes, sometimes less. What I use it for is vocabulary, but not in the way most people do. I don't put single words in it. I put whole sentences I've heard, with the word missing, because a word on its own tells you nothing about how it's actually used. If I only learn that "strike" means to hit, I'll never produce "strike a balance". Why do I find it so useful? Because it's honest with me, in a way. It shows me the cards I keep getting wrong, and it shows them more often. There's no option to skip the uncomfortable ones. Most study methods let you spend your time on what you already know, which feels productive and isn't. The other thing is it takes almost no willpower now. It's attached to the bus ride, so I don't decide to study — I just get on the bus. Honestly, that habit connection has done more for my English than any course I've paid for.