Every skier lives for the day that they awake to look out the window to see a 24 inch deep blanket of the most perfect powder snow. But this condition is rare unless you happen to be in a few geographically blessed areas of the planet where the conditions are perfect.
Snow is very dynamic.
It changes throughout the day. It's structure changes over time. The well rounded skier encounters most of these conditions throughout the skiing season. Let's look at the various conditions, their effect on you, and what you have to do about it. There's not a whole lot you can do to ski hard crust well.