The process of reverting an iPhone, iPad, or iPod Touch operating system to a previous version is technically termed a downgrade. This operation involves uninstalling the currently installed iOS version and reinstalling an older one. For example, a user might choose to revert from iOS 17 back to iOS 16.
Reverting to a prior iteration of the operating system is sometimes desirable due to software glitches introduced in the latest release, compatibility issues with older apps, or a preference for the older version’s user interface. Historically, Apple has discouraged this practice, making the process progressively more complex over time, primarily due to security considerations and to encourage adoption of the newest features and security patches.