Piracy, or raiding is the act of going to settlements then burn and kill everything and everyone. That's the basic concept. When raiding you can have different concepts. Maybe you're trying to burn the huts they made from the wood they stole from you? Or maybe you want revenge. This could even be simple as killing everyone. Either way it makes other players mad and you might want to look out if you ever raided before.
Things NEEDED for raiding.
- Anything that starts a fire