A motorcycle saddle is a term for a motorcycle seat in some parts of the world. It is a seat for carrying a rider and, possibly, a passenger, and which is attached to a motorcycle often but not exclusively, behind the fuel tank.
There are several types of saddles used on motorcycles. Most common is the "dual saddle" or "benchseat" which is used on the majority of motorcycles today. It allows both the rider and passenger to be seating fore and aft on a single saddle.
Dual saddles, that is two separate saddles (and often independently sprung), are less common today, but were used extensively early in the 20th century.
A recent innovation that combines the two, as seen on the R1200RT, is where there are two saddles but they are installed adjacent to each other.
The solo saddle is used on motorcycles that will not carry passengers. These include racing motorcycles, off-road motorcycles, and certain historic motorcycles. There are many popular manufacturers of aftermarket saddles including Mustang Seats and Corbin.