Salmon are a polyphyletic grouping of fish in the family Salmonidae. Most salmon are anadromous, hatching out in a gravel nest called a "Red" in a fresh water stream, then swimming out to salt water and growing to full size on a marine diet. After 2-5 years (depending on species) at sea they swim back to the stream where they hatched based on a combination of magnetic navigation and an acute sense of smell. Most Salmon return to the exact stream where they hatched.
Salmon was an important canned fish product before the wide spread popularity of canned tuna. Since the advent of salmon farming salmon has become the most popular fresh or frozen fish eaten by american families.