Fifty years after the eclipse flight of 1973, the knowledge of the solar corona has made great progress, which is presented to the reader in Part II of the book. This Chapter begins with a global description of this part of the solar atmosphere, named corona. It outlines its two components, namely the hot gaseous one (called K) and the cold dusty one (called F), extending in space at large distances from the solar surface. Then this Chapter focuses on the K corona with its complex properties and fine structures, where magnetic fields play a decisive role. The study of the K corona and its phenomena can be done from observatories located in space and sending their data to the scientists on Earth. Such telescopes, not needing total eclipses, can be equipped with coronographs to observe the bright corona, but can also detect ultraviolet and X radiation emitted by the hot K corona. The solar wind, which consists of particles (electrons, protons…) emitted by the corona in space and reaching the Earth, was discovered in the 1960s and is heavily studied by these instruments. This continuous survey of the Sun’s activity and the coronal phenomena is considerably helping to understand the impact of the solar activity on the Earth and its space environment, such as auroras, communications, spacecraft safety and so on.