Homeless shelters are a type of homeless service agency which provide temporary residence for homeless individuals and families. Shelters exist to provide residents with safety and protection from exposure to the weather while simultaneously reducing the environmental impact on the community. They are similar to, but distinguishable from, various types of emergency shelters, which are typically operated for specific circumstances and populations—fleeing natural disasters or abusive social circumstances. Extreme weather conditions create problems similar to disaster management scenarios, and are handled with warming centers, which typically operate for short durations during adverse weather.

Homelessness or houselessness – also known as a state of being unhoused or unsheltered – is the condition of lacking stable, safe, and functional housing. The general category includes disparate situations, such as living on the streets, moving between temporary accommodation such as family or friends, living in boarding houses with no security of tenure, and people who leave their domiciles because of civil conflict and are refugees within their country.