Question: Scientifically....what is odour and why is it here?

Rachel McMullan answered on 11 Nov 2015:

Hi
An odour is anything that activates your sense of smell. Odours activate your sense of smell which sends messages to your brain to tell you more about your environment. Sensing and responding to odours is an important part of mating, avoiding dangers, identifying good things to eat and loads of other things.