Sogou is a leading market provider of search engine, Chinese input, and mobile internet products and services. Sogou had 521 million users in December 2015, making it the second largest Chinese internet company. Sogou’s products include Sogou Keyboard, a search engine, a web browser and smart hardware. Sogou Search has a series of vertical search channels, including Weixin Search, Zhihu Search, Sogou Mingyi, English Search, Academic Search. In the fourth quarter of 2016, Sogou English Search was upgraded, making it the first cross-language search engine globally to help Chinese search for and read medical, scientific and cultural information in English.