A Protein-Protein Interaction Network (PPIN) is a visual representation of how proteins interact with each other within a biological system. These interactions are crucial for various cellular processes, including signaling, metabolism, and immune responses. By mapping these connections, researchers can better understand the complex relationships that govern cellular functions. In a PPIN, each protein is represented as a node, while the interactions between them are depicted as edges or lines connecting the nodes. This network can help identify key proteins, known as hubs, that play significant roles in maintaining cellular health and can be potential targets for drug development.