Welll, that's a long and complex subject. And, it's one that has already been relatively well written up on Wikipedia
Now, I know that's not really the point of asking a question in a community like this, but the subject covers more ground than I can pull from memory, so I'd just be borrowing from online sources to build the answer that someone already did better than I would.
But, the subject is one that I've looked into before. For various reasons, I had a bit of hatred for the word, and I tend to like to understand the few things I hate so that I can hate them with efficacy. The wiki version matches my memory of things pretty much exactly, though my reading was originally before the internet was a thing the average person had access to. Which isn't much of a reassurance since I'm just a random asshole, but that's all I got lol.