Final answer:
A collection of domains grouped together in hierarchical structures and sharing a common root domain is called the taxonomic classification system.
Step-by-step explanation:
A collection of domains that are grouped together in hierarchical structures and share a common root domain is called taxonomic classification system. In biology, the taxonomic classification system is used to organize organisms into different levels of classification, starting from the most inclusive category, such as domain, to the most specific, such as species. For example, the three domains of life are Bacteria, Archaea, and Eukarya, each containing kingdoms, phyla, classes, orders, families, genera, and species.