We briefly review the history of distributed acoustic sensing (DAS) as applied to geophysical problems over the past 20 years, including a bibliography of about 900+ DAS-related papers and abstracts. First, we introduce some general reviews and introductory papers on DAS to provide readers with an overview of DAS technologies and their various applications. Second, we discuss geophysical applications of fiber Bragg grating (FBG) based DAS systems. We describe 10 major geophysical applications of DAS technologies based on Rayleigh backscattering systems in Part 3 of this chapter. We then share some of the open problems and promising areas of research in the hope of promoting future development of DAS as a geophysical tool.