Length

Length  is one of the physical quantities measured by the seven SI base units.

It most commonly refers to the longest dimension of an object. In engineering and physical sciences the quantity length refers to distance. In the International System of Units (SI) length is measured in terms of the speed o f light.

Some of the most common SI units that measure length are the meter or metre, the centimeter, the yard, the foot, the mile and the kilometer.

The astronomical unit, light year and parsec are units for measuring very large distan ces in space.

The angstrom and micron are units for measuring microscopically small distances.

Length is used to measure a single dimension. Area is used to measure two dimensions and volume is used to measure three dimensions.
The symbol for Length is l