Skunks are notorious for their strong odor, which is sometimes difficult to describe to those who have not experienced it. Anyone who has run over a skunk or had pets sprayed by one is familiar with the intense smell, along with various techniques for getting it out of fur and upholstery. The odor is caused by a combination of chemical compounds which these animals can release from their scent glands when under stress or attack. In addition to smelling awful, the spray can cause vomiting and have effects similar to tear gas. As an interesting side note, the spray is also phosphorescent, so it will glow in the dark.
The smell of skunk spray is caused by sulfurous compounds called thiols which combine to form a substance called mercaptan. These thiols have a strong odor, and mix with other chemicals which make the scent stick. This is why animals who have been sprayed sometimes have a faint odor for several weeks, because although the thiols have been mostly neutralized, trace amounts of them still cling to fur. The chemicals which cause skunk spray to cling are used in cosmetics and perfumes for lasting odor power, after the thiols have been removed.
Skunks use the volatile fluid defensively, and it is highly effective. Most animals who have had run ins with skunks avoid the distinctive black and white mammals forever after, thanks to the retching and eye irritation that result from the spray, aside from the intense smell. When skunks are frightened or cornered, they will spray the viscous fluid, sometimes as far as 15 feet (five meters). Killing skunks will also cause them to release mercaptan, due to the muscle relaxation which accompanies death.
Knowing what causes the smell helps to determine what can be used to get rid of it. The thiols must be oxidized into odor neutral sulfonic acid, and a number of things can be used to accomplish this. If the skunk smell is on pets or people, a mild oxidant like hydrogen peroxide and baking soda, or vinegar, should be used. Hydrogen peroxide is the most effective, although it may bleach the pet's fur slightly. Getting rid of the odor is well worth enduring a slightly odd color for a few weeks.
If something which is not alive has been sprayed, such as a deck or piece of furniture, bleach is the most suitable way to get rid of the smell. The bleach will also, of course, affect the color of the object it is used on, so make sure to apply it evenly to make the effect look deliberate. Otherwise, you may have to dispose of the item altogether. Contrary to popular belief, tomato juice is not effective at eliminating the smell.