The differences between automations and triggers highlight two different aspects of your support workflow: time and action. You want to have a clear understanding of when you should use an automation and when you should use a trigger.
Automations within Zendesk Support are specifically time-based. Use them when you want an action to automatically happen according to a timeframe set up in your workflow. Automations run every hour on all your tickets that are not closed.
As the example shows, your support workflow should have some time requirements -- whether they are specific goals of when you'll respond to a request; or more general expectations about the time a ticket needs to remain solved before you can officially close it.
One way to think about when and how to set up an automation is to write your support workflow and indicate if you have any time requirements associated with any of the steps. Say you want to send out a reminder email to your customer if you've been waiting for information from them for over three days. Perfect time for an automation. Rather than having to remember to send that reminder out; or manually go through your tickets, the automation can automatically keep you on schedule.
Triggers within Zendesk Support fire when other specific actions have taken place. Triggers are run through every time a ticket state is changed and triggered if the changes match the conditions defined in the trigger.
Use triggers when you want certain actions to take place only when some other actions have taken place. For example, you want to send out a particular answer to a question when that question comes in. If another type of question comes in, you want another set of actions to take place. Every time a ticket is touched, changes attributes, or has a comment added, the system checks if any of the trigger conditions match the change and fires them off.
To set up your triggers, take that same support workflow that you created for automations and map out how those steps connect. At all those connection points think about whether you can automate the process.
You might not be able to automate the research it takes to troubleshoot a ticket for instance, but you can automate the ticket's escalation. When the agent assigns the ticket to another group, for instance, you can create a trigger that fires off an email to the members of that group.