Kilogram is a unit of measurement for weights. Experts say mass instead of weight. The kilogram therefore indicates how heavy something is. Together with the metre, it is one of the most important units of measurement.
The kilogram is abbreviated to "kg": instead of five kilograms, one writes 5 kg for short. One kilogram is 1000 grams. The prefix "kilo" therefore means 1000, but is often used as an abbreviation for kilogram, i.e. for 1000 grams. 1000 kilogrammes is called a tonne. One gram divided by 1000, i.e. one thousandth of a gram, is one milligram.
The word "gram" itself comes from the Greek and actually means letter. Even the ancient Greeks used it to denote a weight. Today, however, the ancient Greek "gram" would weigh about one and a quarter grams.
Our current kilogram comes from the time of the French Revolution, around 1800, when it was said that a litre of water weighed exactly one kilogram. A vessel is one litre if it is 10 centimetres high, 10 centimetres wide and 10 centimetres deep.
An old unit of measurement is the hundredweight. But it is not understood in the same way everywhere. In some areas it is equal to one hundred kilograms. In other areas, fifty kilograms is one hundredweight. One hundred kilogrammes is then a quintal.