IOS 5

iOS 5 is the fifth major version of Apple's mobile operating system, iOS. It came after iOS 4, and was replaced by iOS 6, which was released on September 19, 2012. The current version of iOS 5 is iOS 5.1.1.
History.
iOS 5 was announced during Apple's Worldwide Developers Conference (WWDC) 2011. Support was dropped for the iPhone 3G and the iPod Touch (2nd generation), and devices that are supported are the iPhone 3GS and later, the iPod Touch (3rd generation) and later, and the first generation iPad and later.
When the iPhone 4S was announced on October 4, 2011, the release date for iOS 5 was also announced. iOS 5 was released on October 12, 2011.
The iPhone 4S already had iOS 5 installed on it, but other devices had to have the update installed through iTunes. At first, many people could not install iOS 5 because they got error messages when they tried to download it. This was because Apple's servers could not keep up with the number of people who are downloading the update.
Features.
iCloud.
Apple's cloud-based service, iCloud, came as part of the iOS 5 update. This feature allows users to sync their music, pictures, videos, and more across all of their devices that have iCloud on them. Each user is given 5 gigabytes of storage for free, but they are allowed to sync unlimited amounts of music, apps, books, and photos.
New apps.
A new feature called iMessage, built into the Messages app, allows anyone with an iOS device to send unlimited messages to people with iOS 5. It also allows iPhone users to send text messages to people who don't have an iOS device. The Messages app used to be only on the iPhone, but iOS 5 brought it to the iPod Touch and iPad.
The Reminders app allows users to make lists and alerts that can be based on a date or a location.
The Newsstand app is not a real app, but it is a folder that shows the newspapers and magazines that the user is subscribed to.
Other new features.
iOS 5 allows devices to sync with iTunes wirelessly for the first time, without being connected to a computer. iOS devices can also be activated and updated over a wireless network for the first time.
In iOS 5, you can get to the camera quickly from the lock screen swiping up on the camera icon. Users can get to the camera without having to enter a passcode, but you can only use the camera. At first, you had to double-click the home button on the lock screen to get to the camera button, but it was changed in iOS 5.1 so that you could swipe up on the camera button.
Notification Center was introduced in iOS 5, and it also changed how notifications are displayed. Instead of a message that appears in the middle of the screen, stopping what was going on at the time, they appear in a banner on the top of the screen. You can access Notification Center by swiping down from the top of the screen, where it is hidden, and it shows notifications that happened in the past.