When buffering polygon features, negative buffer distances can be used to create buffers inside the polygon features. When using the planar method, you can improve the accuracy of buffers created with projected inputs using a projection that minimizes distance distortion, such as an Equidistant Conic or Azimuthal Equidistant projection that is geographically appropriate for your input. In some cases, this may take more time than the geodesic buffer created using the planar option, but the result is a buffer that more accurately matches the shape of the input feature. If you are concerned about the shape of your buffers and how closely their shape matches the original input features, this option is recommended, particularly when your input data is in a geographic coordinate system. This creates buffers that more closely represent the shape of the input features. The shape-preserving geodesic buffer densifies the input features before creating the output geodesic buffers. The geodesic method creates a shape-preserving geodesic buffer regardless of the input coordinate system. If the input features have a geographic coordinate system, geodesic buffers will be created.If the input features have a projected coordinate system, Euclidean buffers will be created.The planar method automatically identifies the method to use based on the coordinate system of the input features.The Method parameter determines how buffers are created. Geodesic buffers may appear unusual on a flat map, but when displayed on a globe, these buffers will look correct. The spatial reference (map projection) of your input features distorts distances to preserve other properties such as area.Your input features are dispersed (they cover multiple UTM zones, large regions, or the entire globe).You should always consider creating geodesic buffers in the following circumstances: Distances are calculated between two points on a curved surface (the geoid) as opposed to two points on a flat surface (the Cartesian plane). Geodesic buffers account for the actual shape of the earth (an ellipsoid, or more properly, a geoid).Euclidean buffers are referred to as planar buffers. Euclidean buffers are the more common type of buffer and work well when analyzing distances around features in a projected coordinate system that are concentrated in a relatively small area (such as one UTM zone). Euclidean buffers measure distance in a two-dimensional Cartesian plane in which straight-line, or Euclidean, distances are calculated between two points on a flat surface (the Cartesian plane).There are two basic methods for constructing buffers: Euclidean and geodesic. The Method parameter determines how buffers are constructed.