I fist learned about distances in school- class of classical geometry. Of course it was not called classical geometry in school but only geometry. The initial concepts were related to distances between points in a plane, between lines in a plane and between a line and a point in a plane. A plane, as you know, is a 2-dimensional (2D) space. In high school, this concept was extended to 3-dimensional space (3D). The concept of distance basically gives an idea of how far (or how close) are two things (lines, points) from (to) each other. What I learned was “**2-norm distance**” (the typical Euclidean distance):

* *I learned about Hamming Distance during my undergraduate courses on electronics communication. However, it is only during research that I learned a *lot more* about distances. My first surprise came when I heard about distances in a class on image processing. You can use distances to measure similarity between images! Of course the definitions and methods to calculate those distances were also different. Since then I have learned about distances being one major way of* identifying similarities* between objects or classes of objects. The central idea behind all these different kinds of distances (not just in image processing) remains the same: to measure how far the objects are from each other in some respect. For instance, in psychoanalysis “** Emotional Distance**” is the degree of emotional detachment from some person or events;

**Czekanovski-Dice**

**distance**is used to compare two audio waveforms

*x*and

*y*in time domain etc. If your distance from the world of distances is not big ;), you might want to try reading the Dictionary of Distances.