This guide provides the official definition of youth homelessness as developed by the Canadian Observatory on Homelessness. It discusses why a definition of youth homelessness should be distinguished from adult homelessness. For young people, homelessness not only involves the lack of stable housing but also the absence of a home where they are embedded in relations of dependence. The report provides a typology of homelessness and housing insecurity: unsheltered, emergency sheltered, provisionally accommodated, and at risk of homelessness. An appendix is provided for the full typology. The report outlines the key differences within the youth homelessness population in terms of age, sex, gender identity, sexual orientation, and ethnicity. It discusses the different pathways to youth homelessness: individual and relational factors, structural factors, and systems failures. The report discusses the short- and long-term effects homelessness may have on youth related to physical and mental health, exploitation and victimization, criminality and street lifestyles, and lack of education from school dropout. The report also lists challenges faced by young people due to the lack of adequate services and resources. Canada has signed four core United Nations human rights agreements related to homeless youth.