What are Trigger Tokens? Marketo describes in this article which trigger tokens are available for Interesting Moments. But there’s more to it.
Let’s take one step back first: What is a Trigger Token? It is a token that can be used in a flow step of a triggered Smart Campaign. And it references attributes of the trigger itself.
Let’s say your trigger is

Then in your Flow Step the token {{trigger.name}} will resolve to the name of the email that was clicked.
And that Trigger Token can not only be used in an Interesting Moment, it can also be used e.g. in a Change Data Value Flow Step or a Sales Alert Email. (I wonder if it can be used in the “Send Email” Flow Step, but I’m too lazy to find out. I just don’t see a use case for this).
Okay, now we have seen what we can use the Trigger Token for in the Flow. But what about the trigger? In the above mentioned article, Marketo lists some, but there are more that are not listed here. For instance: Data Value Changes. (This is a side note in this article.)
What can we use this for?
Well, a client of ours just asked us to create a Sales Alert that should go out when an important field on a contact was changed by Salesforce. Looked something like this:

Now, in the Alert we could say:
Hey Sales Person,
there was a change on your contact in the field “{{trigger.name}}”.
I’m not saying this is a revelation of biblical proportions, but hey: Yesterday I didn’t know, but now I do. 🙂