Derived from the Latin word 'uncia' (one-twelfth), originally referring to the width of a human thumb. 1 inch = 2.54 centimeters (internationally defined in 1959). Widely used in the U.S. and U.K. for screen sizes (e.g., '15.6-inch laptop'), pipe diameters, and tire specifications. Although China uses centimeters, inches remain standard for labeling electronic displays.

Derived from the Latin word 'uncia' (one-twelfth), originally referring to the width of a human thumb. 1 inch = 2.54 centimeters (internationally defined in 1959). Widely used in the U.S. and U.K. for screen sizes (e.g., '15.6-inch laptop'), pipe diameters, and tire specifications. Although China uses centimeters, inches remain standard for labeling electronic displays.