Services (formerly called channels) are IFTTT’s fundamental construction blocks. They portray primarily a sequence of information from a particular web service similar to eBay or YouTube.
Services may also define regulated behavior with some APIs, such as SMS. They can sometimes depict weather or stock data. Each service has a set of triggers and activities.
Triggers are an applet’s “this” component. They are the triggering objects of the action. For instance, you can get a notification based on a keyword or sentence from an RSS feed.
Actions are an applet’s “that” component. They are the resulting output from the trigger input.
IF recipes (applets/services)
Applets are the predicates made from Triggers and Actions (formerly known as recipes). For example, an IFTTT app can send the photo to your Dropbox account (action) if you like a picture on Instagram (trigger).
Do recipes (applets/services)
Ingredients are fundamental information from a trigger — for instance, from the email trigger ; topic, body, attachment, date of receipt, and address of the sender.