Taxonomy organises living organisms into a nested hierarchy of increasingly inclusive groups. The seven main taxonomic ranks from most specific to most general are: Species (most specific — individuals that can interbreed), Genus (group of closely related species), Family (group of related genera), Order (group of related families), Class (group of related orders), Phylum/Division (group of related classes), Kingdom (most inclusive — e.g., Plantae, Animalia). Each rank is characterised by shared features that become less specific at higher levels. For plants, the term Division is used instead of Phylum, though both are acceptable.

Mango (Mangifera indica) serves as an excellent example for understanding plant classification. At the species level, indica refers specifically to the cultivated mango; the genus Mangifera contains about 65-70 species of tropical trees, most native to South and Southeast Asia. The family Anacardiaceae contains ~700 species in about 82 genera, mostly tropical trees and shrubs, many producing irritating resins. The order Sapindales encompasses 9 families and about 6,000 species of trees and shrubs that often produce secondary metabolites including alkaloids, terpenes, and resins. The class Dicotyledonae (or Magnoliopsida in more modern classification) represents a large and diverse group of flowering plants. The division/phylum Angiospermae (flowering plants) is the dominant plant group on Earth, with over 300,000 known species characterised by flowers, fruits, and enclosed seeds.

Each taxonomic rank reflects a progressively broader level of evolutionary relationship and shared characteristics. Species: organisms sharing the same gene pool and capable of interbreeding to produce fertile offspring. Genus: groups species that share a very recent common ancestor and many structural features. Family: groups genera with common evolutionary heritage, often sharing distinctive structural characteristics (e.g., all Anacardiaceae produce a resinous sap). Order: groups families that share common features though more distantly related. Class: a very broad grouping — Dicotyledonae encompasses a huge diversity of plants. The practical value of taxonomy extends beyond mere classification — it helps predict properties of unstudied organisms based on their relatives, guides drug discovery (plants in the same family often produce similar secondary metabolites), aids conservation planning, and provides a universal language for scientists worldwide to communicate precisely about specific organisms.

Classical taxonomy, as represented in NCERT textbooks and this examination, uses the traditional Linnaean hierarchical system with ranks like Kingdom, Phylum, Class, Order, Family, Genus, Species. Modern phylogenetic taxonomy (cladistics) uses molecular data (DNA sequences) to establish evolutionary relationships and may use different groupings. For example, modern classifications recognise that Dicotyledonae as traditionally defined is paraphyletic (does not include all descendants of a common ancestor), and has been replaced by more precise groupings like eudicots, magnoliids, etc. in the Angiosperm Phylogeny Group (APG) classification. However, for NEET examinations, the traditional NCERT classifications are followed.