What is meant by rights in rem and rights in personam?

– These terms are derived from the Roman terms, “action in rem” and “action in personam.” A right in rem is available against the whole world but a right in personam is available against a particular individual only. Rights in rem are negative, while most rights in personam are positive. A right in personam corresponds to a duty imposed upon determinate persons, while a right in rem corresponds to a duty imposed upon persons in general.