Dogs attraction to other dogs secreting

The urine and feces of dogs contain pheromones that other dogs can smell.  The purposes of these pheromones is "to induce specific reactions (behavioral and emotional), including sexual behaviors, aggression, fear-related behaviors, and avoidance reactions."  (This quote comes from an article by a veterinarian on

A dogs urine and feces is it's one ID. Other dogs can recognize each other through this smell. In addition to WenKroy's great answer, urinating, mostly in males, is also a way to mark territory. By smelling the urine a dog can realize he might be careful because he's entering another dog's territory.

The answer is quite simple - they are using urine to create smell which tells on their genetic attributes.

Mike123. 

My dog always sniff the feces and urine of the other dogs outsife our houston galleria apartments. He will always use the restroom near the area where other dogs have. I wonder why they always to this where another dog has?