Cancer Stem Cells (CSCs) or tumor-initiating cells are a subpopulation of cells within the heterogenous tumor with the potential for self-renewal and differentiation into various cell lines. They also have a high tumorigenic potential in all tissues and organs of the body compared to other stem cells. CSCs reside in special microenvironments that are referred to as the niche. CSCs niches are comprised of different types of cells that cause CSCs to be survived and their features to be improved. In this review article, CSCs features, their separation and identification methods and bilateral relationship between CSCs and niches have been examined. Also, major signaling pathways such as Wnt/βcatenin, Notch, Hedgehog and Hippo that are frequently altered in CSCs and provide a supportive role for CSCs, and the therapeutic targets of these pathways, that are effective in eradicating CSCs and cancer treatment, have been studied.