Whiskers on dogs and cats are actually sense organs called vibrissae. While the portion that extends out from the animal’s face does not have nerve cells, the base of the whisker is hypersensitive.
Dogs, cats and other whiskered critters use their whiskers to gather all sorts of information much in the same way that we use our sense of touch to gather information. Whiskers may even prevent curious creatures from sticking their noses in places they don’t belong because the length of whiskers can help a cat or dog determine whether or not their body can fit through an opening.
Read more of what I learned about dog whiskers while researching an article I wrote for the Nest pets titled Do Groomer’s Trim Dogs’ Whiskers?