This document describes the Spatial Design Network Analysis (SDNA) Plugin for QGIS. It summarizes network analysis techniques like those developed by Euler, Burgess, and Christaller. It outlines the features of the sDNA toolbox, including statistics on network buffers and discrete and continuous space analysis. The document provides examples of using sDNA for epidemiology, modeling travel flows, and machine learning to combine multiple transportation behaviors. It demonstrates how sDNA can explain a large percentage of cycle transportation patterns based on urban design factors alone.