Mnemosyne (named for the Greek goddess of memory, Mnemosyne) is spaced repetition software developed from 2003 until the present. The software is similar to SuperMemo, commercial software developed by Piotr Wozniak.
Mnemosyne uses an early version of the SuperMemo algorithm, SM-2, with some modifications that deal with early and late repetitions.
Proponents of spaced repetition software claim that by allowing algorithmic scheduling of learning reviews, long-term memorization of items is aided.
Mnemosyne also voluntarily collects data from its users. This data is made freely available and is a research project on long-term memory.
Each day, the software displays each card that is scheduled for repetition. The user then grades their recollection of the card's answer on a scale of 0-5. The software then schedules the next repetition of the card in accordance with the user's rating of that particular card and the database of cards as a whole. This produces an active, rather than passive, review process.