reading, more efficient editing and creation of cards through batch editing, modifying the GUI, simplifying import of flashcards from other digital sources, adding an element of gamification, etc. Shared decks While Anki's user manual encourages the creation of one's own decks for most material, there is still a large and active database of shared decks that users can download and use. Available decks range from foreign-language decks (often constructed with frequency tables) to geography, physics, biology, chemistry and more. Various medical science decks, often made by multiple users in collaboration, are also available. Comparisons Anki's current scheduling algorithm is derived from SM-2 (an older version of the SuperMemo algorithm), though the algorithm has been significantly changed from SM-2 and is also far more configurable. One of the most apparent differences is that while SuperMemo provides users a 6-point grading system (0 through 5, inclusive), Anki only provides at most 4 grades (again, hard, good, and easy). Anki also has significantly changed how review intervals grow and shrink (making many of these aspects of the scheduler configurable through deck options), though the core algorithm is still based on SM-2's concept of ease factors as the primary mechanism of evolving card review intervals. Anki was originally based on the SM-5 algorithm, but the implementation was found to have seemingly incorrect behaviour (harder cards would have their intervals grow more quickly than easier cards in certain circumstances) leading the authors to switch Anki's algorithm to SM-2 (which was further evolved into the modern Anki algorithm). At the time, this led Elmes to claim that SM-5 and later algorithms were flawed which was strongly rebutted by Piotr Woźniak, the author of SuperMemo. Since then, Elmes has clarified that it is possible that the flaw was due to a bug in their implementation of SM-5 (the SuperMemo website does not describe SM-5 in complete detail), but added that due to licensing requirements Anki will not use any newer versions of the SuperMemo algorithm. The prospect of community-funded licensing of newer SuperMemo algorithms is often discussed among users. However, there exists a greater focus on development of the software itself and its features. The latest SuperMemo algorithm in 2019 is SM-18. Some Anki users who have experimented with the Anki algorithm and its settings have published configuration recommendations, made add-ons to modify Anki's algorithm, or developed their own separate software. Mobile versions The following smartphone/tablet and