The straight back blade is what knife makers consider the standard or base style of all blades. It has a straight spine and a traditional curved belly. This type of design is often used in Hunting, Fillet, Steak, and even Butter Knives as this general purpose blade makes it a great fit for most people where the knifes function isn't necessarily specialized. Being the 1st known blade design is why this type of blade is considered the "standard".