Corylus is a genus of deciduous trees and shrubs commonly known as hazels. These plants are primarily found in the Northern Hemisphere and are recognized for their round, edible nuts, which are often referred to as hazelnuts. The most well-known species is Corylus avellana, which is cultivated for its nuts and is also used in landscaping. Hazels typically grow in a variety of habitats, including woodlands and hedgerows. They are characterized by their broad, heart-shaped leaves and catkins, which are the flowering structures. In addition to their culinary uses, hazelnuts are rich in nutrients and are often used in products like Nutella and various desserts.