A full tang katana refers to a katana sword where the tang extends throughout the entire length of the handle. The term "tang" refers to the portion of the blade that extends into the hilt or handle of the sword.

In a full tang katana, the tang is a solid piece of metal that runs from the tip of the blade all the way to the end of the handle. This construction provides structural strength and stability to the sword, making it more durable and less prone to breaking or snapping under stress.

The handle of a full tang katana is typically constructed around the tang. The handle material, such as wood or synthetic materials, is securely attached to the tang, usually using pins or bolts. The handle is often covered with a wrapping material, such as traditional tsuka-ito (cotton cord) or synthetic alternatives, for improved grip and aesthetics.

The full tang construction is highly desirable in functional and practical swords, as it ensures a solid connection between the blade and the handle, increasing the overall strength and stability of the sword. It allows for better control, handling, and transfer of force during sword techniques and strikes.

When considering a katana, particularly for practical use or martial arts training, a full tang construction is generally preferred as it signifies a higher level of quality and durability. It ensures that the sword is less likely to break or separate at the blade-handle junction, providing a more reliable and safer weapon.