Who or what exactly is an Arduino?
It takes a little work to find out. You have to click down two levels from the home page or the FAQ section to read your first explanation.
That’s one of the problems throughout the site: it takes a bit of work to find out what each thingamajig, gizmo, widget, or doohickey does.
Subsites seceding from the site
Large sites like Arduino that have many contributors belonging to different groups often evolve into a collection of subsites. This pattern can cause confusion when the global navigation dissapears, losing connection to the main site. The deeper they go, the more lost a visitor gets.