The Trigger Event indicates the kind of statement that activates the trigger. It can be one of the following:

Insert
The trigger is activated whenever a new row is inserted into the table. For example, INSERT, LOAD DATA, and REPLACE statements.

Update
The trigger is activated whenever a row is modified. For example, UPDATE statement.

Delete
The trigger is activated whenever a row is deleted from the table. For example, DELETE and REPLACE statement. However, DROP TABLE and TRUNCATE statements on the table do not activate the trigger.