Which military branches have Admirals?

Can somebody explain to me which branches of the military have rank levels called 'Admirals'? I find the rank structures fascinating, especially those that reach into the stratosphere of 'Admiral' level. Also, what roles do these admirals usually play in their respective branches?

In the United States military, the rank of 'Admiral' is primarily used in the U.S. Navy and the U.S. Coast Guard. The U.S. Public Health Service Commissioned Corps, and the National Oceanic and Atmospheric Administration Commissioned Officer Corps also use this rank.

The rank of Admiral in the Navy and Coast Guard is a four-star flag officer rank, the highest possible rank in peacetime. The equivalently ranked position in the Army, Air Force, Space Force and Marine Corps would be General.

Admirals typically have vast amounts of responsibility, which often includes commanding large fleets or serving as high-level military strategists. They might also perform crucial administrative tasks and develop military operations across the globe. Some admirals even reach positions in the upper echelons of the Department of Defense, where they play key roles in crafting broad defense policy.

It's worth pointing out, though, that each military branch has its own distinct structure and nomenclature for ranks. Even though the branches share some rank names like "admiral" or "general", the associated roles and duties can sometimes differ.