Protein-Protein Interaction Networks (PPINs) are complex systems that illustrate how proteins interact with one another within a cell. These interactions are crucial for various biological processes, including signal transduction, immune responses, and cellular structure maintenance. By mapping these interactions, researchers can better understand cellular functions and identify potential targets for drug development. In a PPIN, each protein is represented as a node, while the interactions between them are depicted as edges connecting these nodes. Tools and databases, such as STRING and BioGRID, help scientists visualize and analyze these networks, providing insights into the roles of specific proteins in health and disease.