Person Related Changed - Triggers (How?)

Summary

Which mechanism allows triggers to occur

Content

I'm aware that we can utilize person related changes to create triggers which then creates a potential life event.

When creating the person related changes you can select columns from pre-determined tables and set the expected Old Value vs New Value.

My question is, what is happening on the back end that allows this functionality to exist?  Is it some form of user/webhook that allows functional setup?

Any technical insight on the this functionality would be greatly appreciated!

Keith Velilla