International Systems of Units "SI"
Definition:
There are seven based units that define measurements that are accepted around the world as the standard unit of measurement.
Length comes the metric system and has the meter (m) for it's base. The metric system is based on the powers of ten and uses decimals not fractions as parts of wholes.
Mass also uses the metric system as a base and it's standard is the kilogram (kg). Mass is also easily confused with weight and they are not the same. Mass is the amount of matter whereas weight is the amount of matter with the influence of gravity.
Time is measured in seconds (s). There are sixty second in a minute, sixty minutes in one hour and 24 hours in one day. There are 365.25 days in a Earth year. There is a leap year every four years to make up the .25 day on the calendar.
Luminosity is measured in candela (cd). Luminosity represents the brightness of light from an object.
Amount of substance is measured in moles (mol). A mole is define as the amount of atoms in one mole of a Carbon 12 atom. The number which is recognized is 6.02 X 10 to the 23rd atoms.
Temperature is measured in Kelvin (K). Kelvin can be derived by the formula K = C + 273.15. Where C represents Celsius.
Electrical Current is measure in ampere (A)