A DB3 file is a database file created by SQLite, a self-contained, serverless, zero-configuration, transactional SQL database engine. It is a popular choice for embedded systems, mobile applications, and small to medium-sized databases. DB3 files store data in a structured format, allowing for efficient querying and manipulation using SQL commands. They are often used to store application settings, user data, and other persistent information. The SQLite format is platform-independent, meaning that a DB3 file created on one operating system can typically be opened and used on another. SQLite is known for its small footprint and ease of use, making it a versatile choice for various applications where a full-fledged database server is not required. The .db3 extension is one of several common extensions used for SQLite database files; others include .db, .sqlite, and .sqlite3.