The tool used by scientists to classify organisms is called a taxonomy. It's a system for naming, defining, and grouping organisms based on shared characteristics.

Here's a breakdown:

* Taxonomy: The science of classification.

* Taxonomic Hierarchy: A hierarchical system of grouping organisms into increasingly inclusive categories, starting with the most specific and ending with the broadest.

* Taxonomic Ranks: The levels within the hierarchy, from most specific to least specific:

* Species: The most basic unit of classification, a group of organisms that can interbreed and produce fertile offspring.

* Genus: A group of closely related species.

* Family: A group of closely related genera.

* Order: A group of closely related families.

* Class: A group of closely related orders.

* Phylum: A group of closely related classes.

* Kingdom: A group of closely related phyla.

* Domain: The broadest category, grouping organisms based on fundamental cellular characteristics.

While "taxonomy" refers to the classification system itself, tools used by scientists to develop and visualize this system include:

* Phylogenetic Trees: Diagrams that show the evolutionary relationships between organisms.

* DNA Sequencing: Analyzing the genetic code of organisms to determine their evolutionary relationships.

* Morphological Comparisons: Examining the physical characteristics of organisms to identify similarities and differences.

By using these tools, scientists can create a comprehensive and organized understanding of the diversity of life on Earth.