A duplex is a property that has two conjoining units. Some are side-by-side while others are on separate floors. Most look like two houses that have been combined on one side. Duplexes that appear stacked, usually look more like townhouses. They are most commonly found in the N.E. part of the country, however they can be located in any location throughout the country. Duplexes are also similar to a triplex, fourplex, quadplex or quadruplex.
Duplexes appear much like a smaller version of an apartment. The main difference between a duplex and an apartment is the combined number of units and that duplxes more closely resemble a house.