How many dwarf planets exist in our solar system?
There are 5 dwarf planets in our solar system.
Since Pluto was reclassified as a dwarf planet back in 2006 there are now 5 dwarf planets in our solar system, their names being: Ceres, Pluto, Haumea, Eris and Makemake. All of these are located in the outer solar system near or otherwise in the Kuiper belt with the exception of Ceres which can be found in the asteroid belt which is roughly halfway between the orbits of Mars and Jupiter. Other planets have been found which may be dwarf planets but have yet to be classified so.
What makes a dwarf planet different to a planet is the fact that dwarf planets haven't cleared the neighbourhood around their orbit, but planets have.