What is the beeping alarm thing when you walk out of a shop?

The beeping alarm you hear when walking out of a shop is typically a theft prevention system designed to deter shoplifting. These systems use electronic tags or labels attached to merchandise, which trigger alarms if not properly deactivated or removed at the checkout. When someone exits the store and the tags are still active, the sensors at the exit detect them, resulting in the beeping sound. It's a security measure to protect retailers from losses.