Which feature allows users to switch between different devices without losing progress?

The feature that allows users to switch between different devices without losing progress is Handoff. Handoff is part of Apple’s Continuity suite, designed to create a seamless experience across multiple devices, such as iPhones, iPads, and Macs, by enabling users to start a task on one device and then pick up exactly where they left off on another.

For instance, if you're composing an email on your iPhone, you can easily switch to your Mac and continue writing the email without losing any of your work. This feature relies on Bluetooth and Wi-Fi connectivity and requires that both devices are signed into the same Apple ID, making it an integral tool for users who frequently work across various Apple devices.

While Continuity is a broader umbrella term that encompasses Handoff along with other features like Universal Clipboard and Instant Hotspot, Handoff specifically refers to the continuity of tasks across devices. Other options, such as App Clips or AirDrop, serve different functions and do not facilitate task continuity in the same way.