Mistake notebook
Your wrong answers come back at the right time. Answer a card correctly and it moves to a later box; miss it and it returns tomorrow. Questions you get right five times are marked mastered.
How the revision schedule works
The notebook uses a Leitner-style system with six boxes. New mistakes start in box one and are due immediately. A correct answer moves a question to the next box, which waits longer before the next review: one day, three days, a week, two weeks and a month. A wrong answer sends it back to the start.
This spacing is based on how memory works: reviewing just as you are about to forget strengthens recall far more than rereading the same page repeatedly.
Your data stays with you
Everything is stored in your own browser. There is no account and nothing is uploaded. Use the same browser to keep your history, because clearing site data deletes the notebook.