T-Bone
The T-bone is a steak cut of beef. It consists of a T-shaped bone with meat on each side. The larger side contains meat from the strip loin, whereas the smaller side contains the tenderloin. T-bone steaks from the rear end of the tenderloin contain a much larger section of the tenderloin, and are called porterhouse steaks. (NB, in British Commonwealth countries, only the strip loin side is called the porterhouse, and the tenderloin side is called the filet. Thus a "porterhouse steak" order results in a boneless steak that is the equivalent of strip steak.)
There is little agreement among experts on how large the tenderloin must be to call a T-bone a porterhouse; some steaks with a large tenderloin may be called a mere T-bone in some restaurants and steakhouses. However, there is general agreement the tenderloin can be no thinner than the diameter of a US quarter dollar coin (24.26 mm) to be classified as a porterhouse.
Due to their large size and the fact that they contain meat from two of the most prized cuts of steak, t-bone steaks are generally considered one of the highest quality steaks, and prices at steakhouses are accordingly high. Porterhouse steaks are even more highly valued due to their large tenderloin.