Ulta's 21 Days of Beauty sale is finally here. Now through September 18, expect flash sales every day with 50% off different products, from makeup and skincare to hair and beauty tools. But here's the exciting twist: Alongside these daily 24-hour markdowns, the retailer is also introducing Weekly Beauty Steals, giving you an entire week to snag discounts on additional cult favorites. Ahead, our team of editors has combed through the entire sale calendar to highlight the deals truly worth your attention—and your money.