Consumer-based, community-controlled, nonprofit outpatient facilities that provide basic health care including physical examinations, immunizations, family planning, nutrition assistance and diagnosis and treatment of common ailments for low income people, people who are homeless or uninsured/underinsured or other medically underserved populations that are geographically, economically and culturally challenged. Services are generally provided on an ability-to-pay basis. In the U.S., most community clinics are part of the network of Federally Qualified Health Centers, and many are known as "free clinics".