The ThinkPad line runs right through the history of computing, far before Lenovo took over IBM's laptop business. It was always a line for business users, coined from a portmanteau of the leather-bound notepads with IBM's "THINK" slogan and that the first ThinkPad was actually a tablet computer. Since then, it's gone into space, has a devoted following, and has likely created more corporate documentation than any other laptop brand.