Nutella is the brand-name of a chocolate and hazelnut spread created in the 1940s by Ferrero (best known for their Ferrero Rocher sweets which are filled with Nutella). It is used for sandwiches among other things.
It is popular in Europe; less so in the United States. Nowadays, in Paris, Crêpes filled with Nutella spread are popular snacks available at food vendors on many street corners.
Gnutella, a piece of computer software, supposedly derives its name from Nutella.
