This course introduces the concepts and techniques fundamental to Web-based GIS mapping, which refers to the rapidly growing field involving the development of interactive maps for desktop and mobile users of the World Wide Web. Beginning with an overview of Web technology and an introduction to common Web mapping concepts and methods including the client-server model, slippy maps and tile map services (TMS), data models, and browser-based vector graphics, students learn to develop interactive Web maps and applications using several industry-standard Web mapping software platforms including ArcGIS Online and Mapbox Studio. Emphasis is placed upon using and extending existing Web mapping platforms to facilitate rapid development of professional quality Web maps and applications. Basic use of Web markup language (HTML) and stylesheets (CSS and similar formats) is taught and incorporated in several exercises. Practical applications are provided throughout the course.