A duplex consists of two individual residences within one building. The units can be side by side, sharing a common wall, or stacked vertically, with one unit on the ground floor and the other above it, connected by separate entrances realtor.com+2. Each unit usually has its own kitchen, bathroom, and living spaces, and the floor plans may be identical or vary in style and size Zillow+1. Duplexes often resemble a single-family home from the exterior, with two front doors and sometimes shared or divided outdoor spaces like yards or patios