The Small Magellanic Cloud (SMC) is a dwarf galaxy
in the Local Group about 200,000 light-years away,
apparently orbiting the Milky Way (though this depends
upon determination of their velocity relative to each other,
which is a measurement subject to improvement).
It has a diameter of about 19,000 light-years
and has hundreds of millions or a few billion stars.
Characteristics:
Both Magellanic Clouds were formerly called irregular,
but are now often classified as a type of spiral galaxy,
a single-armed type termed a Magellanic spiral galaxy
(indicated by an appended lower-case "m").