  Among exoplanets, the small-size population constitutes the dominant one,
with a diversity of properties and compositions ranging from rocky to gas
dominated envelope. While a large fraction of them have masses and radii
similar to or smaller than Neptune, yet none share common properties in term of
orbital period and insulation with our ice giants. These exoplanets belong to
multi-planet systems where planets are closely packed within the first tenth of
AU and often exposed to strong irradiation from their host star. Their
formation process, subsequent evolution, and fate are still debated and trigger
new developments of planet formation models. This paper reviews the
characteristics and properties of this extended sample of planets with radii
between $\sim$ 1.6 and 4.0$_\oplus$. Even though we still lack real
Neptune/Uranus analogues, these exoplanets provide us with key observational
constraints that allow the formation of our ice giants to be placed in a more
general framework than the sole example of our solar system.
