Telescopes are optical instruments used for observing distant objects, primarily celestial bodies like stars, planets, and galaxies. Telescopes come in various types, including refractors, reflectors, and compound models, each offering different optical characteristics and advantages. Refractor telescopes are known for their crisp images, while reflector telescopes provide more light-gathering power for deep-sky observations. Many modern telescopes are equipped with features like computer-controlled mounts for easier sky tracking. Shopping online for telescopes offers a range of models suitable for beginners, intermediate users, and advanced astronomers, with varying aperture sizes and features.