There are several base units at the heart of the International System. The following lists the seven base units:

• meter (distance)
• kilogram (mass; related to weight)
• second (time)
• ampere (electric current)
• Kelvin (temperature)
• mole (amount of substance)
• candela (intensity of light)

Still other SI units—called SI derived units—are defined algebraically in terms of the above fundamental units. All the base units are consistent with the metric system called the MKS, or mks system, which stands for meter, kilogram, and second. Another metric system is the CGS, or cgs system, which stands for centimeter, gram, and second.