A chef's knife is a large knife with a smooth, unserrated blade cutting just about everything in the kitchen that does not require a serrated knife. One good kitchen knife or chef's knife can suffice and it is worth investing in a good one. The blade needs to be curved as the knife may be used in some instances by rocking the blade across items which are being cut up, using the blade as a fulcrum. The blade should be big enough that the handle is carried a sufficient distance from the chopping board that you don't graze your knuckles when rocking the knife or cutting or slicing. A large blade is very efficient for cutting vegetables and herbs up very small.