On August 24th, the Sun unleashed an awesome M class flare (an M5.6 to be exact). The flare itself wasn't aimed at Earth, but the sunspot that created it is still there and is rotating so Earth is right in the line of fire. If the sunspot erupts again while Earth is in the line of fire, we'll probably have some wonderful auroras an could have some minor disruptions with our communications satellites (though, only for a few minutes). Below are three different videos that were captured by various sun-gazing observatories.
The classification system is on a logarithmic scale. The letters, from least to most powerful, are classified as A, B, C, M, or X, where an X class flare is 10 times more powerful than an M class which is 10 times more powerful than a C class and the pattern continues.
Most solar flares aren't a cause for concern for most people. The only things we need to worry about are people and equipment in space. Keeping a close eye on the Sun helps us to put our satellites in safe mode, and our people in a safe zone, so the storm can pass without incident. There are some doomsday scenarios revolving around solar flares, but most of the time everybody on Earth can just sit back and enjoy the aurora.