Our sun is a massive ball of burning hydrogen, a giant nuclear furnace. With the incredible heat generated by the sun, massive jets of plasma tend to shoot out from its surface, bent into enormous arches by magnetic fields. Every now and then these magnetic fields will get tangled up in each other and can become so warped that they snap, sending out masses of charged particles known as coronal mass ejections (CMEs), or solar flares.
Sometimes these CMEs will fly at the earth, but they are usually deflected by the magnetic field that surrounds the planet. If the electromagnetic charge of the flare is aligned parallel to the earths magnetic field, then the flare will be deflected, however, if the charge is aligned opposite to the earths, the fields will connect and the charged particles will be directed to the earths poles, often causing the phenomenon known as auroras.
For a while now NASA has been observing the sun using a variety of satellites, among which are the Solar Terrestrial Relations Observatory and the Solar Dynamics Observatory. The goal of these satellites is to help us understand more how the sun works and to allow us to predict when solar flares will occur. When a solar flare hits our planet, orbiting satellites must be shut down because the charged particles in a solar flare can cause surges in electrical equipment which could disable a satellite. Because of this prediction is key.
The sun is known to go through stages in solar storm activity, and some predictions say that our sun is going to become much more active soon. With an increase in the frequency and severity of solar winds, there is a concern about the effect that it could have on our civilization. If a solar flare were to make it past the planets magnetic field, it would cause massive power surges in the electrical grid and could blow out transformers, sending us into darkness. If we were to lose power, there would be a whole host of problems that we would have to deal with. Food would go bad and electrical gas pumps would stop working. Transportation would become very difficult, and starvation would be a real concern. Apart from that, if power were to be cut off to nuclear power plants, they would be in serious threat of melt down. Nuclear power plants have back up generators to keep the nuclear rods that boil water cool, but there is a significant threat that we wouldn't be able to get the power back up before those generators ran out of fuel to pump water.
There are several things that can be done to help protect us against collapse after a solar flare. One of the biggest problems is that transformers take years to manufacture, and we don't have many replacement ones laying around. Production of replacement transformers is key. Already there is a Recovery Transformer project (RecX) funded by the Homeland Security in the U.S. that is developing temporary transformers. Another step that must be taken is surge protection, so that our electronics aren't fried when a solar flare hits. The Neutral Capacitor and Bypass Device is already in existence and is designed to block massive DC currents and reroute AC currents caused by normal electrical problems. More funding still needs to go into these devices before they can protect us from solar storms, and public concern is ultimately what will drive this research.