What is CoinMarketCap used for?

So, I'm curious to know, what exactly is CoinMarketCap used for in the world of cryptocurrency? I've heard it mentioned quite often, but I'm not entirely sure of its purpose. Is it a tool for investors to track the prices and market caps of different digital currencies? Or does it offer more than just that? I'd appreciate it if you could shed some light on the matter and explain how CoinMarketCap fits into the overall cryptocurrency ecosystem.