Cork is an impermeable, buoyant material, a prime-subset of bark tissue that is harvested for commercial use primarily from Quercus suber (the Cork Oak), which is endemic to southwest Europe and northwest Africa. Cork is composed of suberin, a hydrophobic substance, and because of its impermeability, buoyancy, elasticity, and fire resistance, it is used in a variety of products, the most common of which is for wine stoppers. Portugal produces approximately 50% of cork harvested annually worldwide, with Corticeira Amorim being the leading company in the industry. Cork was examined microscopically by Robert Hooke, which led to his discovery and naming of the cell.

There are about 2,200,000 hectares of cork forest worldwide; 32.4% in Portugal, and 22.2% in Spain. Annual production is about 300,000 tons; 61.3% from Portugal, 29.5% from Spain, 5.5% Italy.

Once the trees are about 25 years old the cork is stripped from the trunks every ten years. The trees live for about 200 years. The first two harvests produce poorer quality cork.