Solar storms happen all the time and they greatly vary in magnitude. Occasionally, solar storms are quite strong and can disrupt satellite and HF communications for many hours. On rare occasions, solar storms can be extremely strong and potentially cause disastrous damage to our technological infrastructure. Knowing the effects and how to prepare for these extreme solar storms is important in mitigating the effect on us and how we recover in the aftermath.
The below webpages provide a good introduction to solar storms: