Here are some common use cases for the announcement bar:
Informational
Notify customers about current shipping delays or changes to delivery timelines
Provide updates on the status of an ongoing sale or promotion
Promotional
Advertise limited-time sales, discounts, or special offers
Promote new product launches or restocked popular items
Highlight seasonal or holiday promotions (make use of Shopify's automatic discounts)
Urgency and Scarcity
Countdown to the end of a flash sale or limited-stock promotion
Notify customers of a deal expiring soon to create FOMO
Show a countdown for cart reservations ("Your cart is reserved for 10:00 minutes")