A pine is any conifer in the genus Pinus (/ˈpaɪ.nəs/) of the family Pinaceae. Pinus is the sole genus in the subfamily Pinoideae. The species are evergreen trees or shrubs with their leaves in bunches, usually of 2 to 5 needles. The seeds are carried on woody cones, with two seeds to each cone scale.

Pines are widely distributed in the Northern Hemisphere; they occupy large areas of taiga (boreal forest), but are found in many habitats, including the Mediterranean Basin, and dry tropical forests in southeast Asia and Central America. Some are fire-resistant or fire-dependent.

Pine trees provide one of the most extensively used types of timber. The seeds are used to make dishes such as pesto, while retsina wine is flavoured with pine resin.

Pine trees are evergreen, coniferous resinous trees (or, rarely, shrubs) growing 3–80 metres (10–260 feet) tall, with the majority of species reaching 15–45 m (50–150 ft) tall. The smallest are Siberian dwarf pine and Potosi pinyon, and the tallest is an 83.45 m (273.8 ft) tall sugar pine (Pinus lambertiana) located in Yosemite National Park.

Pines are long lived and typically reach ages of 100–1,000 years, some even more. The longest-lived is the Great Basin bristlecone pine (Pinus longaeva). One individual in the White Mountains of California, dubbed "Methuselah", is among the world's oldest living organisms at around 4,800-years old. An older tree near Wheeler Peak, now cut down, was dated at 4,900-years old.

The spirals of branches, needles, and cone scales are arranged in Fibonacci number ratios.

The bark of most pines is thick and scaly, but some species have thin, flaky bark. The branches are produced in "pseudo-whorls", actually a very tight spiral but appearing like a ring of branches arising from the same point. Many pines are uninodal, producing just one such whorl of branches each year, from buds at the tip of the year's new shoot, but others are multinodal, producing two or more whorls of branches per year.

Pines have four types of leaf: