The United States Navy (USN) is the naval warfare

Naval warfare

Naval warfare is combat in and on seas, oceans, or any other major bodies of water such as large lakes and wide rivers.-History:Mankind has fought battles on the sea for more than 3,000 years. Land warfare would seem, initially, to be irrelevant and entirely removed from warfare on the open ocean,...

 service branch of the United States Armed Forces

United States armed forces

The United States Armed Forces are the military forces of the United States. They consist of the Army, Navy, Marine Corps, Air Force, and Coast Guard.The United States has a strong tradition of civilian control of the military...

 and one of the seven uniformed services of the United States

Uniformed services of the United States

The United States has seven federal uniformed services that commission officers as defined by Title 10, and subsequently structured and organized by Title 10, Title 14, Title 33 and Title 42 of the United States Code.-Uniformed services:...

. The U.S. Navy is the largest in the world; its battle fleet tonnage

Tonnage

Tonnage is a measure of the size or cargo carrying capacity of a ship. The term derives from the taxation paid on tuns or casks of wine, and was later used in reference to the weight of a ship's cargo; however, in modern maritime usage, "tonnage" specifically refers to a calculation of the volume...

 is greater than that of the next 13 largest navies combined. The U.S. Navy also has the world's largest carrier fleet, with 11 in service, one under construction (two planned), and one in reserve.