 Fibroblasts are the primary source of extracellular matrix in connective tissues, mediate pathological fibrotic accumulation, and have multiple concomitant biological roles in wound healing, inflammation, and angiogenesis. They also play a role in cancer progression, and specific therapies targeting fibroblast biology are under investigation. This article was authored by Ryan Thomas Kendall and Carol A. Fagulli-Bostwick.