Urban Exploration (often shortened as Urbex) is the exploration of abandoned ruins or not usually seen components of the man-made environment. Many Urban Explorers find decay of uninhabited space to be profoundly beautiful.

The term Lost Places is most frequently used by people performing Urban Exploration of man-made architecture that is abandoned or no longer accessible to the general public. Photography is often used as a medium to communicate discoveries made in those places.

Modern Ruins is a neologism referring to ruins of architecture constructed in the recent past. They are often considered to be representative of accelerated rate of change, not only of their structural makeup or past purpose but also of society as a whole.

Urban Decay is the process whereby a previously functioning city, or part of a city, falls into disrepair and decrepitude. It may feature deindustrialization, depopulation, abandoned buildings and a desolate, inhospitable city landscape.