Network buffer analysis delineates areas reachable within a specified cost along a network—commonly called isochrones for time or isodistances for length. Unlike Euclidean buffers, which draw circles around locations, network buffers expand along passable streets or paths, respecting one-way restrictions, barriers, and slopes. They show the footprint of access from an origin by car, transit, bike, or foot, often at multiple thresholds (e.g., 5/10/15 minutes). Method choices include exact isochrone algorithms or approximations via sampled paths; outputs can be polygons, lines, or grid-based surfaces indicating cumulative opportunity. Properly built, network buffers provide a fairer measure of access to services than simple radii and are vital for equity audits and compliance with standards such as walk-shed requirements around stations.