The classification of a collection of objects generally means that a list has been constructed with exactly one member from each isomorphism type among the objects, and that tools and techniques can effectively be used to identify any combinatorially given object with its unique representative in the list. Examples of mathematical objects which have been classified include the finite simple groups and 2-manifolds but not, for example, knots.
Classification
See also
Characterization, Enumeration ProblemExplore with Wolfram|Alpha
Cite this as:
Weisstein, Eric W. "Classification." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Classification.html