A yew is any tree or shrub of the genus Taxus, belonging to the family Taxaceae. There are approximately eight species of yew, which are ornamental evergreen trees and shrubs distributed across the Northern Hemisphere. Some key characteristics of yew include:

• They have dense, dark green foliage with flat, linear leaves that appear to grow in two rows along the sides of branches.
• Yew trees can range from shrubby forms to trees up to about 25 meters (80 feet) tall.
• The seeds are typically solitary and enclosed in a fleshy, red, cup-shaped structure called an aril.
• Most parts of the yew tree, including foliage and seeds (but not the arils), contain poisonous alkaloids that can be fatal if ingested.
• Yew wood is hard, fine-grained, and has historically been used for making items like archery bows and fine carved articles.
• Some species, particularly the Pacific yew, contain taxol, a compound used in cancer treatment drugs.

Yew trees are often associated with mythology and folklore, commonly found in churchyards, and can live for hundreds or even thousands of years. They are slow-growing but long-lived and moderately resistant to pests. Because of their longevity and association with death and rebirth, yews carry symbolic meanings in many cultures. In summary, a yew is a long-lived evergreen coniferous tree or shrub known for its distinctive foliage, poisonous parts, historical uses, and cultural symbolism. The common European yew is Taxus baccata, often what people refer to as simply "yew".