Homelessness is defined as living in housing that is below the minimum standard or lacks secure tenure. People can be categorized as homeless if they are: living on the streets (primary homelessness); moving between temporary shelters, including houses of friends, family and emergency accommodation (secondary homelessness); living in private boarding houses without a private bathroom or security of tenure (tertiary homelessness). The legal definition of homeless varies from country to country, or among different jurisdictions in the same country or region. 

Source: Wikipedia

Photo Credits: Sandro Lombardo