Microsoft Jet Database Engine

The Microsoft Jet Database Engine is a database engine on which several Microsoft products have been built. A database engine is the underlying component of a database, a collection of information stored on a computer in a systematic way. The first version of Jet was developed in 1992, consisting of three modules which could be used to manipulate a database.

JET stands for Joint Engine Technology, sometimes being referred to as Microsoft JET Engine or simply Jet. Microsoft Access and Visual Basic use or have used Jet as their underlying database engine. It has since been superseded for general use, however, first by Microsoft Desktop Engine (MSDE), then later by SQL Server Express. For larger database needs, Jet databases can be upgraded (or, in Microsoft parlance, "up-sized") to Microsoft's flagship database product, SQL Server.

However, this does not mean that a MS Jet (Red) database cannot match MS SQL Server in storage capacity. A 5 billion record MS Jet (Red) database with compression and encryption turned on requires about 1 terabyte of disk storage space, comprising hundreds of (*.mdb) files, each acting as partial table, and not as a database in itself.

Over the years, Jet has become almost synonymous with Microsoft Access, to the extent that many people refer to a Jet database as an "Access database".

Jet, being part of a relational database management system (RDBMS), allows the manipulation of relational databases. It offers a single interface that other software can use to access Microsoft databases and provides support for security, referential integrity, transaction processing, indexing, record and page locking, and data replication. In later versions, the engine has been extended to run SQL queries, store character data in Unicode format, create database views and allow bi-directional replication with Microsoft SQL Server.

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