Copy pasting from JDBC 3.0 Specification: (See if you can make out any meaning :-) ). 9.1 Types of Drivers There are many possible implementations of JDBC drivers. These implementations are categorized as follows: Type 1 � drivers that implement the JDBC API as a mapping to another data access API, such as ODBC. Drivers of this type are generally dependent on a native library, which limits their portability. The JDBC-ODBC Bridge driver is an example of a Type 1 driver. Type 2 � drivers that are written partly in the Java programming language and partly in native code. These drivers use a native client library specific to the data source to which they connect. Again, because of the native code, their portability is limited. Type 3 � drivers that use a pure Java client and communicate with a middleware server using a database-independent protocol. The middleware server then communicates the client�s requests to the data source. Type 4 � drivers that are pure Java and implement the network protocol for a specific data source. The client connects directly to the data source.
[This message has been edited by Amit Agrawal* (edited September 20, 2001).]