What is the width of narrow gauge?

Narrow gauge typically refers to railway tracks with a gauge (the distance between the rails) that is less than the standard gauge of 1,435 mm (4 ft 8.5 in). Common narrow gauge widths include 1,000 mm (3 ft 3 3/8 in), 762 mm (2 ft 6 in), and 600 mm (1 ft 11 5/8 in), among others. The specific width used can vary depending on regional preferences and historical context. Narrow gauge railways are often employed in areas with challenging terrain or for specific industrial purposes.