Many people are familiar with green tea and black tea, but there's more. The International Organization for Standardization (ISO) recently released a document from Chinese experts classifying tea into six types. The basic tea types are black and green tea, white tea, oolong tea, dark tea and yellow tea, according to the new standard established by Anhui Agricultural University in Hefei, Anhui province. The standardization work was led by Wan Xiaochun, professor and director of the State key laboratory of tea plant biology and utilization at the university. Chen Chuan, a pioneer in tea science, put forward the classification standard as early as in 1979. It has been widely adopted since then but had not become an international standard until March, when the document was released, Wan said during a news briefing earlier this week. The preparation of tea is based on processing fresh tea leaves and aeration. The six tea types can be further processed or reprocessed to create products such as scented tea, compressed tea and instant tea, the ISO document said. The classification will allow consumers, world tea traders and governments to have a clear understanding of the different type of tea through their processing techniques. For the new standard, Wan has been leading a team of Chinese experts and has cooperated with 31 from other countries since 2008 for the compilation, the university said in a news release on Tuesday.