The katana originated in ancient Japan.
What we commonly refer to as "katana" today is actually a specific type of Japanese sword — professionally known as the uchigatana.
The uchigatana is the most iconic style, featured in countless movies, anime, and historical depictions.
However, Japan’s sword-making tradition includes many types of blades, such as the tachi, wakizashi, and tanto.
Katanas are characterized by their natural curvature, which is not manually shaped, but instead formed naturally during clay tempering — a traditional Japanese heat-treatment method.
During quenching, the edge and spine cool at different rates, causing the blade to curve and producing a beautiful hamon (temper line).
The hamon is an essential element when appreciating the beauty of a traditional katana.