The present paper studies the Banach contraction principle for digital metric spaces such as digital intervals, simple closed k-curves, simple closed 18-surfaces and so forth. Furthermore, we prove that a digital metric space is complete, which can strongly contribute to the study of Banach fixed point theorem for digital metric spaces. Although Ege, et al. [O. Ege, I. Karaca, J. Nonlinear Sci. Appl., 8 (2015), 237-245] studied "Banach fixed point theorem for digital images", the present paper makes many notions and assertions of the above mentioned paper refined and improved.