Finding hidden (statistical) structure in unlabelled data, including clustering and feature extraction for dimensionality reduction.
Finding hidden (statistical) structure in unlabelled data, including clustering and feature extraction for dimensionality reduction
Because the items are unlabelled, there's nothing that points toward the "correct" labels, as there is with supervised learning. Unsupervised learning uses methods like clustering and principal components analysis to discover structure.
Reference:
Wikipedia - Unsupervised learning
