A trigger in Oracle is a type of stored procedure that is automatically executed in response to certain events occurring in a database. These events can include actions such as inserting, updating, or deleting rows in a table. Triggers can be used to enforce business rules, perform data validation, or automate certain tasks.To create a trigger in Oracle, you first need to define the trigger's name, timing (BEFORE or AFTER), event (INSERT, UPDATE, DELETE), and scope (ROW or STATEMENT).