What is Tron Classic?

Excuse me, could you please clarify what Tron Classic is? I've heard of Tron, but I'm not entirely sure about the distinction between Tron and Tron Classic. Is Tron Classic a separate cryptocurrency or a fork of Tron? If it's a fork, what was the reason behind it? Also, how does Tron Classic differ from Tron in terms of functionality, market capitalization, and community support? Thank you for your time.