Measurement of length

1. Units of length

1.1. International System of Units

1.1.1. meter

1.1.2. centimeter

1.1.3. kilometer

1.2. Imperial System of Units

1.2.1. inch

1.2.2. foot

1.2.3. yard

1.2.4. mile

1.3. astronomical unit

1.3.1. light year

1.3.2. parsec

2. History

2.1. the olderist unit of length

2.1.1. cubit

2.2. usage

2.2.1. distance

2.2.2. dimension of an object

3. Todays

3.1. used in every sphere of life to enable fair trading conditions

3.2. to develop new and improved products

3.3. defined in term of the speed of length