Trigger on Task (before insert) - Example 1

// This simple trigger changes the value of the standard Activity field 'Type' on task records to 'Email' if, before insert, the task is BLANK. 
// This trigger could be improved upon by creating a method in a helper class to keep the trigger logicless. 

trigger TaskWithBlankType of Task (before insert) { // 'before insert' is the trigger context variable 
    for (Task t : Trigger.new) { // for loop - for all tasks which match the trigger context variable...
        if (t.Type == null) {  // if branch nested in the for loop. If the type on the task is empty...
            t.Type = 'Email'; // change the value of the Type to 'Email'. Remember: no DML operations required on 'before' trigger  context variables
        }
    }
}