In order to help us to understand the world, we measure and record an enormous amount of information. This book covers units used both in everyday life and in scientific subjects, complete with explanations, conversion equations and conversion tables. Systems of measurement were created to quantify natural phenomena and to allow us to deal more effectively with everyday life. People have measured lengths, weights and time since earliest times. Accurate measurements of weight were needed for trading goods and of length for marking out property and for building - and for these measurements to work they have to be based upon agreed standards. From those early measurements, many other units have been developed, each designed for a particular purpose. This book covers units used in the following areas: numbers; length and distance; areas; volume; time; speed; mass; weight and density; energy; force; temperatures. It provides / units and their sub-division / conversions to other types of unit / formulae for quick calculations / an explanation of how the unit is measured / what the unit is used for In addition there are listings of abbreviations used for units, instruments used for measuring, and individuals who invented particular units.