What is Panini?

What is Panini - actually one should ask - What are Panini?
Panini are sandwiches made in a panini grill. In English panini is referred to as one sandwich as well as multiple sandwiches (paninis) when actually the individual sandwich is a panino and multiple sandwiches are panini.
In Italian, panino referrs to a small bread roll and a panino imbottito refers to a sandwich (which literally means stuffed panino).
Panini are tradionally made with ciabatta bread, sliced meat and cheese, lightly buttered and grilled.
Special grills, called panini grills are used to make these sandwiches. These grills, which are common though-out italy, are gaining populatity here in America.