DB is a database abstraction layer providing:
- an OO-style query API
- portability features that make programs written for one DBMS work with other
  DBMS's
- a DSN (data source name) format for specifying database servers
- prepare/execute (bind) emulation for databases that don't support it natively
- a result object for each query response
- portable error codes
- sequence emulation
- sequential and non-sequential row fetching as well as bulk fetching
- formats fetched rows as associative arrays, ordered arrays or objects
- row limit support
- transactions support
- table information interface
- DocBook and phpDocumentor API documentation

DB layers itself on top of PHP's existing database extensions.