.ACCDB file format
An ACCDB file is a database created with Microsoft Access 2007 or later. It typically contains data organized into tables and fields and may also include custom forms, SQL queries, and other data. ACCDB files replaced .MDB files. ACCDB files are similar to MDB files used in previous versions of Access, but support additional functionality, which is led to their replacement of MDB files. Some enhancements of ACCDB files include the ability to store file attachments and other binary data, multi-valued field support, database encryption, and integration with MS Outlook and SharePoint.
The .ACCDB file format is analogous to the .docx and .xlsx formats of Microsoft Word 2007 and Excel 2007, respectively. In fact, the .accdb format is more widely known as the “Access 2007” file format. Databases created or saved as .accdb files cannot be opened by versions of Microsoft Access prior to 2007, which includes Access 95, 97, 2000 and 2003. Databases created in the earlier .mdb format can be converted to .accdb databases by simply opening them in Access 2007 or a later version and saving in the newer file format. Of course, the newer versions of Access are also fully backward-compatible with older .mdb files. The .ACCDB format supports some features not available in the .mdb format, such as multivalued fields, data macros, ability to include attachments in the database, integration with Sharepoint and Outlook, and publishing to Access services. However, some older features like replication and user-level security are no longer supported in the newer format.