A type of distance metric, which is the sum of the absolute differences between the coordinates of two points, $d(a,b)=\sum _{i=1}^n\left|a_i-b_i\right|$. Named after driving from A to B on an orthogonal street grid, such as that of Manhattan, New York. Also known as the taxicab metric. This is a very simple distance metric with certain very specific uses, e.g. in high-dimensional spaces or machine learning. Serves as a basis for several other, more sophisticated distance metrics