Kreise, or circles, are simple geometric shapes defined as the set of all points in a plane that are equidistant from a central point, known as the center. The distance from the center to any point on the circle is called the radius. Circles are fundamental in mathematics and appear in various fields, including physics and engineering. In everyday life, circles can be found in objects like wheels, coins, and plates. They are also significant in art and design, often symbolizing unity and completeness. The study of circles involves concepts such as circumference, area, and the relationship between angles, making them essential in both theoretical and practical applications.