The i OS 11.2.2 includes further fixes for the "Meltdown" and "Spectre" vulnerabilities that came to light last week.
Meltdown and Spectre are serious hardware-based vulnerabilities that take advantage of the speculative execution mechanism of a CPU, allowing hackers to gain access to sensitive information.
You can check the version of i OS your device is currently running by launching the Settings app, then tapping on General followed by About and looking at the number on the Version line.
Before updating, you'll want to have a current backup of your device. Technically, your device should be backing up your device every night while its charging, but it's not a bad idea to have a backup made moments before you hit the update button.
From Apple's security support document: Available for: i Phone 5s and later, i Pad Air and later, and i Pod touch 6th generation Description: i OS 11.2.2 includes security improvements to Safari and Web Kit to mitigate the effects of Spectre (CVE-2017-5753 and CVE-2017-5715).
Apple first announced i OS 9, the mobile operating system that runs on the i Phone, i Pod Touch, and i Pad lineups.
While Meltdown was addressed in the i OS 11.2 update, Apple said it would introduce a mitigation for Spectre early this week.
There is no hardware fix for Spectre, so Apple is addressing the vulnerability using Safari-based software workarounds.