Why is there a need for classification,and what are the bases of classification?

(N/A) $\rightarrow$ There are millions of animal species with diverse structures and forms.
$\rightarrow$ Since over a million species have been described so far,classification is essential to organize and study them systematically.
$\rightarrow$ Classification helps in assigning a systematic position to newly discovered species.
$\rightarrow$ The fundamental bases of animal classification include:
$1$. Arrangement of cells.
$2$. Body symmetry.
$3$. Nature of coelom (body cavity).
$4$. Patterns of digestive,circulatory,and reproductive systems.
$5$. Notochord presence or absence.