Procedures and Functions,Packages and Database Triggers.  

A  Package  is a collection of related procedures, functions, variables and other package constructs together as a unit in the database.

A Database Trigger is procedure (set of SQL  and PL/SQL statements) that is automatically  executed  as  a  result of an insert in,update to, or delete from a table.

Database  triggers  can  be  used  to automatic data generation, audit data modifications, enforce complex Integrity constraints, and customize complex security authorizations.