The litre (or liter; US spelling) is a unit of volume and is a non-SI metric unit with the symbol L).
1 litre is equal to the volume in a cube with edges all measuring 10cm. There are 0.22 imperial gallons in a litre. Conversely, 1 imperial gallon is equal to 4.5461 gallons.
1 litre of water weights exactly 1 kilogram.
After the metric system was introduced in France in 1791, it took a couple of years for the entire country to implement it in everyday use. After much backlash, it was decided that the cubic metre was too big for everyday use. By 1795 it was announced that the former 'cadil' (0.001 cubic metres) had been given a new name; 'litre'.
The US liquid pint is a unit of volume in the US customary system with the symbol pt.
1 US liquid pint is equal to 1/8 US liquid gallon. This is equal to 1/2 US liquid quart, 2 US cups, 4 US gills or 16 US fluid ounces. The SI / metric equivalent is 473.1765 ml.
From the early (1707) adoption of the British wine gallon at 231 in³, the American pint was born. Where all pints are 1/8 of their respective unit system's gallon, that put the US pint at 28.875 in³.