a brand of laptop, originally produced by IBM. The brand is now manufactured and sold by Lenovo.
The ThinkPad is a line of laptop computers originally designed, developed and sold by IBM (1992-2005) but now produced by Lenovo. They are known for their boxy black design, which was modeled after a traditional Japanese Bento lunchbox. Lenovo purchased IBM's personal computer business and acquired the ThinkPad brand in 2005, see Wikipedia Thinkpad.