Linked from
The 23 pages that link to Solar corona, each with the reason it gives.
Solar windBroader topic: The hot corona supplies the particles that escape as solar wind.
Solar flareBroader topic: Most flare energy is released in the corona and its magnetic structures.
SunBroader topic: The corona is far hotter than the photosphere beneath it.
HeliophysicsBroader topic: The corona is the source region of the solar wind and many eruptions.
Solar phenomenaBroader topic: Coronal mass ejections originate in this outer atmosphere.