For those learning or brushing up their Mandarin Chinese, this app can be used to learn vocabularies. The vocabularies are grouped into six levels based on Hànyǔ Shuǐpíng Kǎoshì 汉语水平考试 The Hànyǔ Shuǐpíng Kǎoshì is standardized by China where simplified Chinese characters are mainly used. There are two modes: study and flashcard.