Cancer stem cells is a subpopulation of neoplastic cells within a tumor that exhibits characteristics analogous to normal tissue stem cells, including the capacity for self-renewal and multilineage differentiation. This academic concept and active research area investigates the hypothesis that these rare cells are fundamentally responsible for initiating and propagating tumor growth, mediating resistance to conventional therapies, and driving recurrence due to their unique biological properties and hierarchical organization within the tumor microenvironment, representing a critical target for developing more effective, durable cancer treatments.