A more thorough explanation:

Foster care is a system run by the state where a child who is not safe or stable in their home is taken into state custody and placed in the care of licensed adults who are not their parents or guardians. These adults can be in a group home or a private home with a foster family. The caregivers have a legal duty to take care of the child, but the state has legal custody. Foster care is meant to be temporary until the child can be reunited with their parent or guardian or placed with a permanent family.

• A child is removed from their home because their parent is abusing drugs and neglecting them. They are placed in a group home with other children in foster care.
• A child's parent is incarcerated and there is no one else to take care of them. They are placed with a foster family until their parent is released.
• A child's parent voluntarily relinquishes their rights and places them in foster care because they cannot provide a stable home.

These examples illustrate how foster care is used when a child's home is not safe or stable. The child is placed with licensed adults who can provide a safe and stable environment until they can be reunited with their parent or guardian or placed with a permanent family.