Poaching is the illegal hunting, fishing or harvesting of wild plants or animals. It may be illegal because:

• The game or fish is not in season, usually the breeding season is declared as the closed season when wildlife species are protected by law.
• The poacher does not possess a license.
• The poacher is illegally selling the animal or animal parts or plant for a profit.
• The animal is being hunted outside of legal hours.
• The hunter used an illegal weapon for that animal.
• The animal or plant is on restricted land.
• The right to hunt this animal is claimed by somebody.
• The means used are illegal (for example, baiting a field while hunting quail, using spotlights to stun or paralyze deer, or hunting from a moving vehicle, watercraft, or aircraft).
• The animal or plant is protected by law or that it has been listed as extinct or an endangered (see for example the Endangered Species Act for the USA)
• The animal or plant has been tagged by a researcher

It is currently estimated that the illegal wildlife trade is worth 10 billion US dollars.

Note that only wild animals can be poached. Stealing or killing domestic animals is considered to be theft ("cattle rustling"), not poaching.

Plant poaching is also on the rise. A prominent example is the removal of Ginseng blank">http://www.nps.gov/grsm/naturescience/threats-to-wildflowers.htm growing in the _Great Smoky Mountains National Park. It is estimated that dried wild ginseng plants are worth more that $500 per pound on the black market.

Traditional Chinese medicine often incorporates ingredients from all parts of plants, the leaf, stem, flower, root, and also ingredients from animals and minerals. The use of parts of endangered species (such as seahorses, rhinoceros horns, and tiger bones and claws) has created controversy and resulted in a black market of poachers who hunt restricted animals.