The ground state of a system is the lowest energy state of the system.
The state of a system is dependent on the way electrons are distributed in a chemical species. A distribution that results in the system having the lowest energy is the ground state of the system. Every other distribution configuration is associated with a higher energy state known as an excited state. For example, the ground state of carbon is given by the term symbol 3P, while the term symbols 1D and 1S denote excited states of carbon.
