Homelessness describes the condition of people without a regular dwelling. People who are homeless are most often unable to acquire and maintain regular, safe, secure, and adequate housing, or lack "fixed, regular, and adequate night-time residence." The legal definition of "homeless" varies from country to country, or among different entities or institutions in the same country or region.

The term homeless may also include people whose primary night-time residence is in a homeless shelter, a warming center, a domestic violence shelter, cardboard boxes or other ad hoc housing situation. American Government homeless enumeration studies also include persons who sleep in a public or private place not designed for use as a regular sleeping accommodation for human beings.

An estimated 100 million people worldwide were homeless in 2005. In western countries the large majority of homeless are men (75-80%), with single males particularly overrepresented. In America, LGBT people are over-represented among homeless youth, at 40%.

Read more about Homelessness:  Difficulties in Classification: Lack of Generally Agreed Nomenclature, Assistance and Resources Available To Homeless People, Refuges For Homeless People, Health Care For Homeless People, Tracking and Counting Homeless People, Strategies To Reframe Approaches To Homelessness, Beyond Homelessness, Films About Homelessness