The MDB file extension is primarily associated with Microsoft Access, a database management system (DBMS) from Microsoft. MDB files store the entire database structure, including tables, queries, forms, reports, macros, and modules (VBA code). It's a proprietary format used to organize and manage data in a relational database environment. The file contains the data itself, along with metadata describing the database schema, relationships between tables, and other database objects. MDB files are commonly used for small to medium-sized database applications, often for desktop or small workgroup environments. While newer versions of Access use the ACCDB format, MDB remains prevalent due to its compatibility with older versions of Access and other applications that support the Jet Database Engine. The MDB format has evolved through different versions of Access, with each version introducing new features and improvements. However, backward compatibility is generally maintained, allowing newer versions of Access to open older MDB files. Security features, such as password protection and user-level security, can be implemented within an MDB database to control access to sensitive data.