A telescope is an optical instrument that allows people to observe distant objects by collecting and magnifying light. It typically consists of a set of lenses or mirrors that focus light to create a clear image. Telescopes are commonly used in astronomy to study celestial bodies like stars, planets, and galaxies. There are different types of telescopes, including refracting telescopes, which use lenses, and reflecting telescopes, which use mirrors. The invention of the telescope in the early 17th century revolutionized our understanding of the universe, leading to significant discoveries by astronomers like Galileo Galilei and Isaac Newton.