The standard unit of length in the metric system is the meter. The meter, symbolized as “m,” was originally defined in the late 18th century based on a fraction of the Earth's circumference. It has since been redefined in 1983 based on the speed of light, establishing that one meter is the distance light travels in a vacuum in 1/299,792,458 of a second. The metric system is widely used around the globe due to its simplicity and ease of conversion, as it is based on powers of ten. This makes it particularly useful in scientific, engineering, and everyday measurements.