Is having a samurai sword illegal?

Excuse me, I've been doing some research on samurai swords and their historical significance, but I'm a bit confused about the legality of owning one today. Is it illegal to possess a samurai sword in most places? If so, what are the specific laws and regulations surrounding their ownership? And are there any exceptions or circumstances under which owning a samurai sword would be permissible? I'd appreciate any clarification you can provide on this matter.