This book constitutes the refereed proceedings of the 18th International Symposium on Web and Wireless Geographical Information Systems, W2GIS 2019, held in Wuhan, China, in November 2020. The 8 full papers presented together with 15 progress papers or short papers in the volume were carefully reviewed and selected from 40 submissions. The papers cover topics that range from mobile GIS and Location-Based Services to Spatial Information Retrieval and Wireless Sensor Networks