An au pair's charge refers to the children that an au pair is responsible for taking care of. A few synonyms for this term include "host family children", "ward", or "protege". These terms can be used interchangeably with "au pair's charge" while speaking or writing about this topic. An au pair's charge can be a single child or multiple children depending on the arrangement made between the host family and the au pair. Regardless of the number of children an au pair cares for, they are responsible for their well-being, not just their basic needs but also their holistic growth and development.