Final answer:
The category 'domain' was introduced as an advancement to the original Linnaean taxonomy, expanding the hierarchical system to account for fundamental biochemical differences among all life forms.
Step-by-step explanation:
The category that was introduced as an advancement to the original Linnaean taxonomy is domain. Carl Linnaeus initially organized species into a hierarchical taxonomy, which has since been expanded to include the category of domain, which is more inclusive than his highest category, the kingdom.
The three recognized domains that encompass all life forms are Bacteria, Archaea, and Eukarya, representing a significant addition to the taxonomy as it accounts for fundamental differences in the biochemistry of organisms.
The current taxonomic system now includes eight hierarchical levels: domain, kingdom, phylum, class, order, family, genus, and species. This allows for a more precise classification of organisms, taking into account a wider range of biological data.