Please identify and define the core concepts of systems theory.

Systems theory emphasizes concepts of interconnectedness and complex relationships among multiple parts and elements. In sociology, systems theory is represented by the relationship an individual has with his or her beliefs, and how they interact with society as a whole.
Systems theory is closely intertwined with the theory of evolution. Two versions of systems theory have emerged as a result. One theory argues that society is constantly changing and evolving into a more perfect society. The second theory, also known as structural differentiation, argues that instead of attaining increasing perfection, society is becoming increasingly more complex.
Systems theory is applied to business by examining the relationships between an organization, its employees, the industry, and the market as a whole. In the same way that systems theory can help explain the workings of a society, it can be used to explain the workings of a business. Systems theory can also be implemented to further understand why certain scenarios yield the outcomes that they do.
https://smallbusiness.chron.com/application-systems-theory-business-organizations-73405.html

https://www.britannica.com/topic/systems-theory