The adoption rate of iOS 9 witnesses a spike after Apple introduces brand new emojis in iOS 9.1.

iOS 9 is the ninth edition of Apple's mobile operating system (OS) and it was released to devices on Sept. 16. The new OS does not bring many new features but it focuses more on under-the-hood optimizations.

On Sept. 21, Apple announced that iOS 9 had the fastest adoption rate and over 50 percent of iOS-powered devices have been running the latest OS.

"iOS 9 is also off to an amazing start, on pace to be downloaded by more users than any other software release in Apple's history," said Philip Schiller, senior VP of Worldwide Marketing at Apple.

However, the release of iOS 9.1 on Oct. 21, which brings a number of emojis, has also resulted in higher adoption rate of iOS 9. iDevice users can use regular emojis as well as some new ones. According to Apple, 66 percent of iOS devices are running on iOS 9, 25 percent on iOS 8 and the balance on earlier version of the mobile OS.

The sleuth or spy emoji has a smiley with a hat and a magnifying glass. This emoji can be used when a person is feeling sneaky. The raised hand with spread fingers emoji can be used by users to give a virtual hi-five. A unicorn face, comet, fog, snowman, umbrella, taco and burrito — all of these are some of the few emojis found in iOS 9.1.

Emojis are available for various categories such as smiley, animals and nature, food and drink, and more. Emojis are a simple and easy way of communication and expression with or without using texts. iOS, Android and Windows have different emojis but they all have the same purpose.

The adoption rate of iOS 8 was slow in comparison with the adoption rate of iOS 6 and iOS 7. Apple wants increased adoption rate of iOS 9 and the introduction of new emojis are a good way of enticing people to download the latest version of iOS.