As described in the first chapter of this book, Geomatics should be understood as the discipline that groups mathematical concepts and methodological and technological procedures that can be used to manage spatial data. For civil engineers, this means understanding the concepts and techniques for collecting field data using surveying instruments and determining geospatial data through the algebraic relationship between the measured values of quantities. In this context, it is necessary to understand the basic concepts underlying such procedures before starting any measurement or data modelling process. Therefore, this chapter presents the basic mathematical concepts that the readers should know when collecting geospatial data for their civil engineering projects.