This source, a newsletter titled "You Didn't Know! Keywords for Deeply Understanding Chinese IT," introduces the term BAT, representing China's major tech companies: Baidu (search), Alibaba (e-commerce), and Tencent (social media). It explains that BAT's significance isn't solely based on size, but on their control and distribution of internet traffic and their strategic investments that categorize many other tech companies as belonging to one of the three. The text illustrates this dynamic by detailing how Alibaba defended its e-commerce traffic from attempts by Tencent and Baidu to enter the space, highlighting the "Three Kingdoms" like power balance and competition in the Chinese internet landscape, though noting this structure is evolving.