The popularization and widespread use of computers and communication technologies has led researchers into developing computer-assisted diagnostic and testing systems for use in the enhancement of learning. The use of expert knowledge systems in the teaching process has found significant application in recent years. The use of expert systems (ES) has traversed different areas including work environments. The paper surveys the application of expert knowledge systems today. Essentially, the paper evaluates the opinions brought forth by other authors. Consequently, the paper contrasts the opinions to construct the inherent themes within the development of ES. The discussion touches on issues such as development of the system, the evolution, and the challenges in the development and application of the systems as suggested by other authors. As a conclusion, the paper will observe the main themes emerging from the discussion.