What is a millimeter?
A millimeter is a thousandth of a meter (1/1000) which is the SI (International System of Units) unit of length. It is normally used to measure small lengths like the thickness of a sheet of paper or the dimensions of a small object.
One millimeter is approximately equal to 0.03937 inches (about 1/25th). Presicely there are 25.4 millimeters in an inch and it is often used in science and engineering. It is used in countries that have adopted the metric system.
You may come across millimeters when measuring the size of electronic components, jewelry or even the thickness of a fingernail.
What is a mile?
A mile is an imperial and US unit of length, exactly 1,609.344 meters. The word comes from the Latin mille passus, 'a thousand paces', where a pace was two steps of a marching legionary.
A mile is equivalent to 1760yds or 5280ft.
Road distances in the US and UK are signed in miles, while nearly every other country uses kilometers. Aviation and shipping use the nautical mile instead, which is a different length (1,852 meters).