Does Prime cost money?

Does Prime actually cost money? I've heard so much about it, and it seems like everyone's talking about the benefits it brings. But is it really free, or do I have to pay a certain fee to enjoy its perks? I'm a bit confused because some sources say it's completely free, while others suggest there might be hidden costs. Can you clarify this for me? I'm really interested in signing up, but I want to make sure I'm not going to be hit with unexpected charges down the line. Is Prime really worth it, and if so, how much does it actually cost?