Nature of Geographic Information
This is a free, online textbook that was designed to "promote understanding of the Geographic Information Science and Technology enterprise (GIS&T, also known as 'geospatial')." "This text serves as an assigned reading for registered students in formal Penn State courses. The Orientation section (linked to the Resources menu on the left) familiarizes registered students with the text and with the associated course management system (ANGEL). Links to Chapters 1-9 appear in the Contents menu. Only registered students are entitled to feedback from instructors and to earn academic credit for their participation in the course."