A steak knife is a sharp table knife used to cut steaks and other firm meats. It has a serrated edge and wooden or plastic handle scales.
Steak knives are characterized by their serrated edge. A serrated blade is ground in a wavy line to create pointy "teeth". This increases the knife's cutting performance – the teeth of a serrated blade are curved backward so that they touch the meat at a much steeper angle than a straight blade would. The serrated blade doesn't make a straight cut right away but creates many small tears which are widened and connected with repeated cutting motions. Therefore, serrated blades "rip" instead of cutting – which makes them perfect for firm, resilient materials such as steak. The first steak knives were introduced in the United States after World War II.
Today, steak knives are the only serrated knives among the eating utensils. Until the early 20th century, many table knives had a serrated edge, which increased their cutting performance. This was necessary since stainless steel was not yet used in knife production. The thin blades of many straight-edged table knives did not hold up to high pressure and firm cutting materials. With the introduction of stainless steel after World War I and especially with the introduction of heat-treated stainless steel after World War II, it was possible to make table knives that retained their edge without the need for constant honing.
Stainless steel made serrated table knives mostly obsolete. However, steak knives had been well established at that point and have now become the standard utensil for cutting steaks and other firm meats served on the bone.