Homelessness is the ongoing condition of being without a home. Frequently, the term is applied to people who "sleep rough" (i.e., outdoors in an area they do not own or rent) and to people who reside in very short-term housing intended for those who are otherwise homeless. It can also be applied to people who have insecure housing, such as those residing with a friend temporarily and having no prospect of more permanent housing (Toro 2007). The term "homelessness" can also refer, especially in European usage, to those who have inadequate housing (Edgar 2009). Research on homelessness has a long history (Anderson 1923).