What is a Solar Flare?
A solar flare is one of the three major components of a solar storm. The other two components are solar proton events (SPE) and coronal mass ejections (CME). Not all solar storms produce all three components, but the largest storms tend to. A large enough solar flare can produce a CME so powerful that it not only produces large green auroras in the sky, but also cripple the electrical infrastructure of the world. Our story begins the day before such a storm hits earth.
Here are some great links to websites that explain all about solar flares and other space weather: