Homeless Children and Youth Act of 2021 This bill modifies definitions relating to homeless individuals and homeless children or youth as used by the Department of Housing and Urban Development (HUD) to verify eligibility for HUD homeless assistance programs, including the Continuum of Care program. Specifically, the bill aligns these terms with the definitions of homeless used to verify eligibility for other federal assistance programs. The definitions are also amended to increase access to federal homeless programs by homeless children, youth, and families. Additionally, the community-wide homeless management information system shall be made available to the public on HUD's website.