Newfoundlands are one of the "giant" breeds, looking roughly like a black Saint Bernard. They were originally bred to do draft work (hauling) and to help the fishermen in Newfoundland, Canada, so they are large, strong, and nearly impervious to cold and wet. They also have natural water-rescue instincts; many people have been saved from drowning by a Newfoundland. The record is over 100 lives credited to a single dog who braved icy waters in the middle of a storm to carry a life-line between shore and a foundering ship, thereby saving every soul on board.
Newfoundlands were also used as "Nanny dogs" in earlier times, because they are very gentle and protective with children. In fact "Nana" in the story Peter Pan was a Newfoundland.
My wife and I have two Newfoundlands named Aslen and Nellie. We've joined both the local and national Newfoundland clubs, so if you have any questions about Newfies, please feel free to ask us. If we don't know the answer (and we frequently won't, since these are our first dogs), we can put you in touch with someone who does. Please be patient though, since I don't get to my email every day.
Also, if you ever become aware of a Newfoundland who is in danger of being euthanized or sent to a shelter just because he doesn't have a home, please call us at home at (630) 416-3216 so we can contact Newfoundland Rescue to try to save him.
There are now enough web sites that you can also find lots of stuff in any search engine by looking for "+Newfoundland +dog".