A Cassegrain telescope is a type of reflecting telescope that uses a combination of mirrors to gather and focus light. It features a large primary mirror that collects light and reflects it to a smaller secondary mirror, which then directs the light through a hole in the primary mirror to the eyepiece or camera. This design allows for a compact structure while maintaining a long focal length. The Cassegrain design is popular in both amateur and professional astronomy due to its efficiency and versatility. It is commonly used in observatories and for astrophotography, making it an essential tool for studying celestial objects.