“Save the internet” Net nutrality

This is all I've heard about this week. Everyone saying to save the internet. But what is net nutrality? I dont know. On the internet it tells me that its all websites treating data the same. But I'm confused. Why is everyone freaking out about this? What's the big deal? I've heard that net nutrality will be removed friday. But no one will tell me what that means. If anyone could clarify this for me and tell me why this is such a big deal it would be appeciated.