"It's like the Levi's 501 of personal computing."

In an effort to explain how the ThinkPad brand has sustained 20 years, a sale from IBM to Lenovo, and relentless competition from all sides, Lenovo design VP David Hill turned mostly to analogy. He likened the ThinkPad to jeans, Jeep, and the Porsche 911 — three things that have evolved over time without ever losing sight of their original statement or design. That's the idea behind the ThinkPad.

The ThinkPad line celebrates its 20th birthday today, and just as you probably still wear jeans and could draw a pretty accurate Jeep Wrangler if I asked you to, the ThinkPad has become the rare constant in the technology industry. Nearly everything around it has changed, but ThinkPad has always been the professional-grade black box. In honor of its anniversary, we look back at how the ThinkPad made it to 2012, and whether or not you'll still be using one in 2032.