IFTTT
IFTTT - If This Then Than
IFTTT is a service that allows you to define rules in the style of "if this happens do that", in example "if somebody tags me in a photo on Facebook, send me an email".
This involves a number of components, and IFTTT uses its own lingo that additionally has changed over time (https://ifttt.com/wtf).
A trigger defines the "this" in "if this happens". An action defines the "that" in "do that". Triggers and actions are provided by services (ex-channels). In the above example, Facebook provides a service that can send a trigger if I get tagged in a photo. Some other service can send email to be. An applet (ex-recipe) defines what trigger launches which action. Ingredients are attributes of the trigger and the action.
More technical information under https://partners.ifttt.com/docs.
"To speed things along, we made a small Ruby on Rails application that corresponds with a service that we pre-configure for new IFTTT Partner account." - no I fucking won't! Ruby on Rails was new 10 years ago, and in comparison to Java, it never went anywhere.