J D B C Driver Type Comparison

JDBC Driver Type Comparison
Category	Type 1	Type 2	Type 3	Type 4
Basic Description	JDBC to ODBC Bridge	JDBC using Native Methods	Middleware JDBC Drivers	Pure Java Driver
Requires native install on client	Yes	Yes	No	No
Cross platform	No	Mostly	Yes	Yes
Supports specific DB features e.g. OracleBlob	No	Yes	Usually No	Yes
Requires additional server	No	No	Yes	No

Sun has the following to say about driver types - http://java.sun.com/products/jdbc/driverdesc.html