Triggers in SQL Server are special stored procedures that are automatically executed in response to an event such as an INSERT, DELETE, or UPDATE statement on a given table. They are used to enforce business rules, maintain data integrity, and to audit changes to data.
For example, a trigger could be used to prevent a user from deleting a record from a table if it is referenced in another table. The trigger would check if the record is referenced in another table and if so, it would raise an error and not allow the delete to occur.