Complex compounds (also called coordination compounds) represent a major constituency of chemical species in which a central metal ion is associated with several ligands in a steady assemblage. The study of these compounds and their interactions with the ligands produces compounds that have unusual characteristics, depending on the viewpoint of the occurrences that affect the geometry, stability, and reactivity of the compounds. The field of coordination chemistry, which began to formulate the concept of chemical bonding and the behaviour of metal-ligand complexes, was initiated by Alfred Werner and has transformed the knowledge base of such complexes. The article is concentrated on the theoretical models which define the bonding in the coordination compounds, the Werner Coordination Theory, the Valence Bond Theory, and the Crystal Field Theory. In addition, the article addresses several types of coordination compounds based on diverse rules like metals, ligands, and charge. The uses of coordination compounds are wonderfully heterogeneous and far-reaching, including industrial, environmental, biological, and medical examples. Remarkably, coordination compounds such as cisplatin have been essential in cancer therapy, and others play important functions in oxygen (hemoglobin) and photosynthesis (chlorophyll). The desired potential of coordination compounds is developing with the developments of synthetic techniques and theoretical frameworks, and provides alternative sources for novel innovations in different scientific and industrial activities. In this article, there is a clear review of how coordination compounds are important and what the future holds.