Pine nuts, also called piñón (Spanish: [piˈɲon]), pinoli (Italian: [piˈnɔːli]), or pignoli, are the edible seeds of pines (family Pinaceae, genus Pinus). According to the Food and Agriculture Organization, only 29 species provide edible nuts, while 20 are traded locally or internationally owing to their seed size being large enough to be worth harvesting; in other pines, the seeds are also edible but are too small to be of notable value as human food. The biggest exporters of pine nuts are China, Russia, North Korea, Pakistan and Afghanistan.

As pines are gymnosperms, not angiosperms (flowering plants), pine nuts are not "true nuts"; they are not botanical fruits, the seed not being enclosed in an ovary which develops into the fruit, but simply bare seeds—"gymnosperm" meaning literally "naked seed" (from Ancient Greek: γυμνός, romanized: gymnos, lit. 'naked' and σπέρμα, sperma, 'seed'). The similarity of pine nuts to some angiosperm fruits is an example of convergent evolution.

In Asia, two species, in particular, are widely harvested: Korean pine (Pinus koraiensis) in northeast Asia (the most important species in international trade) and chilgoza pine (P. gerardiana) in the western Himalaya. Four other species, Siberian pine (P. sibirica), Siberian dwarf pine (P. pumila), Chinese white pine (P. armandii) and lacebark pine (P. bungeana), are also used to a lesser extent. Russia is the largest producer of P. sibirica nuts in the world, followed by either Mongolia or Afghanistan. They each produce over 10,000 metric tons (9,800 long tons; 11,000 short tons) annually, most of it exported to China.

Pine nuts produced in Europe mostly come from the stone pine (P. pinea), which has been cultivated for its nuts for over 5,000 years. Pine nuts have been harvested from wild trees for far longer. The Swiss pine (P. cembra) is also used, to a very small extent.

In North America, the main species are three of the pinyon pines: Colorado pinyon (P. edulis), single-leaf pinyon (P. monophylla), and Mexican pinyon (P. cembroides). The other eight pinyon species are used to a small extent, as is gray pine (P. sabineana), Coulter pine (P. coulteri), Torrey pine (P. torreyana), sugar pine (P. lambertiana) and Parry pinyon (P. quadrifolia). Here, the nuts themselves are known by the Spanish name for the pinyon pine, piñón (plural: piñones).

In the United States, pine nuts are mainly harvested by Native American and Hispano communities, particularly in the Western United States and Southwestern United States, by the Shoshone, Paiute, Navajo, Pueblo, Hopi, Washoe, and Hispanos of New Mexico. Certain treaties negotiated by tribes and laws in Nevada guarantee Native Americans' right to harvest pine nuts, and the state of New Mexico protects the use of the word piñon for use with pine nuts from certain species of indigenous New Mexican pines.

Pine nuts will not reach full maturity unless the environmental conditions are favorable for the tree and the cone. The time to maturity varies depending on the species.

For some American species, development begins in early spring with pollination. A tiny cone, about the size of a small marble, will form from mid-spring through the end of summer; this immature cone will temporarily cease growing and remain dormant until the following spring, then grow again until it reaches maturity near the end of its second summer. The mature piñon pine cone is ready to harvest ten days before the green cone begins to open. A cone is harvested by placing it in a burlap bag and exposing it to a heat source such as the sun to begin drying. It takes about 20 days until the cone fully opens. Once it is fully open and dry, the seed can be easily extracted in various ways. The most common and practical extraction method used is the repeated striking of the burlap bag containing the cone(s) against a rough surface to cause the cone(s) to shatter, leaving just the job of separating by hand the seed from the residue within the bag.