SuperMemo is the original software based on the spaced repetition system (SRS) algorithm, designed for maximum efficiency in long-term memorization. It is not a pre-made course but a powerful tool that allows you to create your own flashcards and learning materials. It is renowned for the effectiveness of its algorithm but also notorious for its steep learning curve and dated user interface. This tool is best for highly dedicated, self-directed learners who want ultimate control over their study material.