What is a telescope? It is an optical instrument used to see distant objects. Almost everyone has an intuitive idea that it consists of a tube containing lenses or mirrors that capture a light or distant image, and amplify it, offering details that cannot be seen with the naked eye. By taking a brief tour from its discovery in the early seventeenth century to the present day. We will discover that this simple description falls far short for the modern high-tech telescopes currently in service, and much more for the projects that are underway for the coming years, both in terms of ground-based astronomical observatories, as well as those located in space. The James Webb Space Telescope, which has just entered its operational phase, will significantly boost scientific research, especially in astrophysics and cosmology, offering images and data never seen before. The study of extrasolar planets will also experience a qualitative leap, which will once again bring the presence of rational life in the Universe to the forefront of scientific debate, or whether we are unique.