A subdata base is a subset of a larger, more comprehensive database. It contains a certain number of records or fields extracted from the main database, often with a particular focus. The term subdata base can also refer to a portion of a database that is created for a specific purpose, such as for research or analysis. Synonyms for the phrase subdata base include subfile, segment, subset, sub-collection, and sub-library. These terms all suggest a smaller, specialized part of a larger whole. Understanding subdata bases is crucial when working with large databases as it can help streamline data management and make it easier to analyze specific subsets of data.