Linnaeus classified organisms based on the similarities in their physical characteristics, such as their morphology and anatomy. He believed that organisms could be identified and classified based on their shared characteristics, and he developed a system known as binomial nomenclature, where each species is assigned a unique two-part name consisting of the genus and species. By grouping organisms based on their similarities, Linnaeus created a hierarchical classification system that allowed for the identification and organization of the diversity of life. This system, known as Linnaean taxonomy, is still used by scientists today as the foundation for modern classification.