Following the pattern Mike Worboys began in 2004 by inviting Matt to become a coauthor of the second edition, Matt and Mike welcome Qian (Chayn) Sun on to this third edition as a third author. With a background in geography and GIS, Chayn has brought her own fresh perspective and distinct expertise to the third edition, in particular, in web mapping, cloud computing, critical geography, and machine learning with geospatial information. We hope you will agree that the third edition has succeeded in maintaining the high standards set by the first edition of GIS: A Computing Perspective back in 1994!