Tool: Serrated Knife
A serrated knife is a handheld instrument used for cutting. It has "teeth" along the edge which helps facilitate the easy cutting of food or ingredients. It also relies on a "sawing motion" that drags the knife across the surface of the food as it moves down to slice it.
A serrated knife can be an all-purpose tool. They can cut through bread, cake layers, and slice through tomatoes.
A good serrated knife needs to have a flexible blade, the right length, about 10 - 12 inches long, and serrations that are evenly spaced to make it a great all-purpose knife.
Serrated knifes can't be sharpened using a whetstone. You need to use a serrated knife sharpener that can sharpen those serrated edges.