.accdb File — Microsoft Access Database

ACCDB is the current file format for Microsoft Access databases, introduced with Access 2007 to replace the legacy MDB format. ACCDB files use the Access Database Engine (ACE) instead of the older Jet engine, providing improved security, data types, and features. The format supports all MDB capabilities plus complex data types including multi-valued fields, attachment fields for embedding files directly in records, calculated fields, data macros for trigger-like behavior, and enhanced memo fields renamed as Long Text. ACCDB files support AES-256 encryption for database-level security, improved integration with SharePoint and SQL Server, and the ability to publish databases as web applications through Access Services. The maximum file size remains 2 GB. ACCDB files contain tables, queries (SQL and visual), forms for user interface design, reports for printing, macros for automation, and VBA modules for advanced programming. Microsoft Access remains popular for small business applications, prototyping, and personal databases where a full server-based RDBMS would be excessive. ACCDB is backwards-incompatible with Access 2003 and earlier, requiring the newer Access Database Engine runtime for applications that don't include the full Access installation.