Protein interactions refer to the physical contacts between proteins that occur within a cell or organism. These interactions play crucial roles in a wide range of biological processes, including signal transduction, gene regulation, and the formation of complex molecular machinery. Understanding protein interactions is essential for gaining insights into the underlying mechanisms of cellular functions and diseases. Researchers study protein interactions using various experimental techniques such as yeast two-hybrid assays, co-immunoprecipitation, and protein microarray analysis. This field of research is important for drug discovery and development, as targeting specific protein interactions can lead to the development of new therapies for various diseases.