A data model is a representation of how data is organized, structured, and related in a database. Depending on the purpose and scope of the database, data models can vary in complexity and abstraction. In healthcare informatics, you need to consider the type, source, and format of the health data you want to store, as well as the queries and operations you want to perform on it. There are three common data models used in this field: the relational data model, the hierarchical data model, and the network data model. The relational data model uses tables, rows, and columns to store data and defines relationships between them using keys and constraints. It is effective for structured data such as patient records, lab results, and billing information. The hierarchical data model uses a tree-like structure to store data where each node has a parent-child relationship with other nodes; it is useful for storing naturally hierarchical data such as medical terminologies, classifications, and ontologies. Finally, the network data model uses a graph-like structure to store complex and dynamic relationships such as social networks, clinical pathways, and epidemiological data.