iOS stands for "iPhone Operating System" and is the operating system software that runs on Apples iPhone and iPad devices. It is similar to the software that runs on a computer, controlling how the device functions and providing a platform for other apps to run on. Some of the features of iOS include Wi-Fi, Bluetooth, and cellular connectivity, integrated search support, and VPN support. iOS is responsible for everything that goes on on your iPhone or iPad, such as making phone calls, sending text messages, taking pictures and videos, running apps like Facebook, TikTok, or Instagram, browsing the Internet, and sorting out settings.

To find out which version of iOS is installed on your device, you can go to Settings > General > About on your iPhone, iPad, or iPod touch. You can also find the current software version on your iPhone or iPad in the General section of your phones Settings app. If you tap on Software Update, you can see your current OS version and check if theres an update available and ready to install.