Tailbone protection adds padding over your coccyx—the bone at the base of your spine—and it's specifically designed for backward falls. If you're a beginner, it's highly recommended because newer skiers tend to fall backward more often, and landing hard on your tailbone can cause serious bruising or even fracture.
The trade-off is that tailbone padding adds some bulk, which you'll notice when sitting on chairlifts or resting in the lodge. Some skiers find it uncomfortable, while others barely mind it after a few runs.
If you're an experienced skier who rarely falls backward, you might prefer hip-only coverage for a slimmer, more comfortable fit. But for beginners, older skiers, or anyone with a previous tailbone injury, that extra padding is well worth the slight added bulk. Many impact shorts bundle both hip and tailbone protection together, making it an easy choice for comprehensive coverage.