ThinkPads are a line of business-oriented laptops and tablets developed by Lenovo, and formerly IBM until ~2005. ThinkPads have a distinct black, boxy design.
Thinkpads are an incredible line of computers. Why? Many reasons.
ThinkPads have a rich history as the best-in-class business machines. The ThinkPad brand IBM created with the innovative machines of the 90s is so strong that it still lives on today.
Additionally, ThinkPads are incredibly reliable workhorse computers and have excellent build quality. They're rugged and durable, utilitarian in design, have the best laptop keyboard I've personally ever used, and boast the notorious TrackPoint. They don't skimp on ports.
ThinkPads are also easily repairable and have an excellent second-hand market on sites like ebay and craigslist.