Group theory is a branch of algebra, which studies the properties and structure of abstract algebraic systems (groups). The development history of group theory can be traced back to the beginning of19th century, but there were some budding ideas about groups before that. Group theory is widely used in physics, chemistry, computer science and other fields.

In physics, when group theory is widely used to solve problems such as molecular spectrum, molecular vibration, relativity and crystallography, it shows its extraordinary simplicity and unity.