We provide a brief overview of what has been learnt about the environment of GRBs from absorption-line spectroscopy of their afterglows. In particular, we discuss measurements of the redshifts, HI and metal column densities, the molecular and dust content, and kinematics. Using the detection of absorption-line variability, it is possible to estimate the distance of the neutral absorbing material from the GRB through excitation- and ionization-modelling, which is found to be at least 100 pc away from the GRB. Finally, we examine the possibility of probing the environment closer to the GRB with high-ionization lines.