The metric system is a ecimalised system of measurement. It exists in several variations, with different choices of base units, though the choice of base units does not affect its day-to-day use. Over the last two centuries, different variants have been considered the metric system. Since the 1960s the International System of Units (SI) ("Système International d'Unités" in French, hence "SI") has been the internationally recognised standard metric system. Metric units are widely used around the world for personal, commercial and scientific purposes. A standard set of prefixes in multiples of 10 may be used to derive larger and smaller units. However, the prefixes for multiples of 1000 are the most commonly used.