Triggers are the Custom Apex Code, which will execute the Business Logic automatically based on certain events.

By using Triggers, we can implement the Complex Business Logics, Complex Validations, De-Duplication Processes, and the Complex Transactional Flows.

By using Triggers, we can Perform all the DML operations (INSERT, UPDATE, DELETE, UNDELETE, UPSERT, MERGE) on all object records at a time. And we can retrieve the records from the objects by using SOQL Queries.