What are the old illegal music streaming sites?

I'm curious, could you elaborate on what exactly are the old illegal music streaming sites? I've heard whispers about them, but I'm not entirely sure what they entail. Are these websites where users can access and stream music without paying for it, violating copyright laws? If so, could you name a few examples of these sites that were once popular but have since been shut down due to their illegal nature? I'm particularly interested in understanding the history and impact of these sites on the music industry.