The word "length" means the measurement of distance from one end to the other. Length is needed in science, engineering, and construction purposes. For example, length is used to measure the height of a building or the height of a mountain. Length is also used to measure how far light travels through space or water. However, there are different units for measuring length which can make it confusing.
Units of length are used to measure objects both big and small. The system of measurement that is most commonly used in everyday life is metric. There are different types of metric units depending on the type of measurements they represent. These include centimeters, kilometers, and meters, among many others. Length can be measured using a ruler, tape measure, etc.
There is also the imperial system of measuring length that is common in the USA. These units of measuring length in the imperial system include; miles, yards, feet, and inches.