This pretty much echos' what I found all over the net:
"A chef's knife generally has a blade eight-inches (20 cm) in length and 1 ½ inches (4 cm) in width, although individual models range from 6 to 14 inches (15 cm to 36 cm) in length. There are two types of blade shape, French and German. The far more common German design features a pronounced curve towards the tip of the blade which allows the knife to be rocked up and down, chopping the food with the belly and heel of the blade. The French design is more triangular, with much less curve at the tip and a longer straight section of blade; it is designed to be pulled towards the user, slicing the food instead.Neither style is inherently superior; personal preference will dictate the choice."