Custom events let you define the success type that you want to track.
Although similar to predefined events, custom events let you define your own success metric. For example, if you have a newsletter, your success event could be "Registration." Clearly, "Registration" is not part of the predefined events. By using a custom event, you can track the number of visitors who register for your newsletter. Custom events follow the standard syntax shown below.
The code above shows how to assign an event to the events variable. If you do not modify the event name in the interface, then "event3" would display in the interface.
By default, success events are configured as "counter" events. Counter events count the number of times a success event is set. Some success event uses require an event be incremented by some custom amount. These events can be set either as "numeric" events or "currency" events. You can change the event type using Admin Console.