QGIS/resources/function_help/json/buffer

{
  "name": "buffer",
  "type": "function",
  "groups": ["GeometryGroup"],
  "description": "Returns a geometry that represents all points whose distance from this geometry is less than or equal to distance. Calculations are in the Spatial Reference System of this geometry.",
  "arguments": [ {"arg":"geometry","description":"a geometry"},
                 {"arg":"distance","description":"buffer distance in layer units"},
                 {"arg":"segments","optional":true,"default":"8","description":"number of segments to use to represent a quarter circle when a round join style is used. A larger number results in a smoother buffer with more nodes."}],
  "examples": [ { "expression":"buffer($geometry, 10.5)", "returns":"polygon of the current feature's geometry buffered by 10.5 units"}]
}