SuperMemo is a very old software from Poland with 30 years of development history, and has always been used by many people to learn, memorize foreign language words or examination questions, etc. But properly speaking, it is an auxiliary memory software based on the scientific anti-forgetting algorithm, which can help you memorize anything with 10~50 times of improvement on efficiency.

Anki is a friendly, intelligent spaced (word card) learning system based on the Spaced Repetition theory. It's free and open source, with which you can remember anything, anywhere and efficiently.