Helmets are not the only form of protective clothing available for skiing, there are also plenty of other products available to keep you protected. Below are brief descriptions of the most common.
Back protectors now come in many forms, although generally they are an armadillo sort of construction that lies along the back of your spine. Many back protectors are now built into under jackets, that can also have padding for your chest and shoulders, some even cover the whole upper body providing elbow and forearm protection as well.
Padded Shorts protect your thighs, hips and coccyx, and can make falling in icy conditions a lot less painful. They are normally a mesh kind of construction with the pads in the places that you are most likely to hit if you fall.
Knee pads are not so commonly used as with the amount of movement that is used in the knees, a lot of people find them a bit uncomfortable. Nevertheless if you are worried about hitting your knees they will definitely protect them a lot better.
As with knee pads, elbow pads are not so commonly used as they cover a key joint that moves a lot, but again if you are prone to hitting your elbows they will provide valuable protection.
On to the Basic Mechanics of Skiing section.