A geodesic metric space is a metric space in which any two points are joined by a path isometric
to the real interval
(Bridson and Haefliger 1999).
Such a path realizes the distance
between its endpoints. This condition requires a globally
distance-minimizing path, beyond
local minimization along a curve.
For example, Euclidean space and a connected graph with each edge realized as an interval of length 1, equipped with the path metric, are geodesic metric spaces. The CAT(0) comparison condition further controls distances between points on these paths.