Is RadioShack a real company?

Excuse me, but I'm curious to understand something. Could you please clarify for me if RadioShack is indeed a legitimate, operating company? I've heard some conflicting information lately and I'm just trying to get a definitive answer. With so many businesses and startups popping up and disappearing, it's hard to keep track of which ones are still around. So, is RadioShack truly a real and established company?