What is /4chan/

I'm losing my mind. I don't know what this place is. I don't know why it's part of my chambers except that I've been interested in the culture for a while. I thought it was for /meta/. I thought it was for sharing memes. I thought it was a clone of r/gunpolitics that isn't about guns except when it's about guns. It's all of these and none of these. I am confused. Who is this for? What is the purpose? And most importantly, why do I like it?