This content type is very simple to use, but also quite powerful and versatile. If you have custom html code, either something you've developed yourself or code provided by a service like Facebook, Linkedin, Google, or wherever, just copy and paste that into this content type and it will be included in your page.
In this example, we're including weather from Forecast.io, audio from Soundcloud, a Twitter widget, an Issuu PDF, and a Google map.