Human fibroblasts, also known as stromal cells, have a wide range of fascinating cellular functions and practical applications. Fibroblasts are important cells that secrete a diverse range of paracrine factors that affect cell and tissue homeostasis. Stromal cells secrete extracellular matrix components such as collagens and can remodel the ECM. They are often used as feeder cells to culture other cell types at low density and in co-culture studies to explore the effects of secreted growth factors or cytokines on processes such as wound healing and hormone signaling. Cancer-associated fibroblasts (CAFs) play a role in tumor growth and metastasis, and are being investigated as potential targets for cancer therapy. Fibroblasts can be reprogrammed to induced pluripotent stem cells (iPSCs) that can undergo directed differentiation to a multitude of cell types that resemble primary cells.