This book covers the theory and architecture of modern geographic information systems (GIS), including data collection, modeling, analysis, and visualization principles. It discusses various layers like data layer (raster, vector), database, services layer (WMS, WFS, REST API), business layer (spatial analysis, geoprocessing), presentation layer (desktop, web, mobile), standards (OGC, ISO), interoperability, scalability, security, performance, API, and middleware. It also delves into distributed and cloud architectures supporting real-time services