Why flashcards work
Flashcards leverage two of the best-evidenced learning techniques: active recall (forcing yourself to retrieve an answer rather than re-reading it) and spaced repetition (revisiting cards you find hard more often). The question-then-flip format on this tool is built around active recall — you commit to an answer before you reveal it.
Your decks, your data
Decks are stored in your browser's local storage on this device. They survive refreshes and revisits, but they aren't synced anywhere — so for anything important, use Export to save the deck as a JSON file. You can import that file on another device or keep it as a backup.