The International System of Units (often abbreviated to SI from the French name ‘Le Systeme International d’Unites’) defines the standard unit of any physical quantity in terms of seven base quantities. These base quantities are:
Metre – the unit of length, denoted by the symbol m. Note that length is represented by ‘l’.
Kilogram – the unit of mass, denoted by the symbol kg. Note that mass is represented by ‘m’.
Second – the unit of time, denoted by the symbol s. Note that time is represented by ‘t’.
Ampere – the unit of electric current, denoted by the symbol A. Note that electric current is represented by ‘I’.
Kelvin – the unit of thermodynamic temperature, denoted by the symbol K. Note that the thermodynamic temperature is represented by ‘T’.
Mole – the unit for the amount of substance (or the number of particles of a given substance, denoted by the symbol mol. Note that the amount of substance is represented by ‘n’.
Candela – the unit of luminous intensity, denoted by the symbol cd. Note that luminous intensity is represented by ‘Iv’.