Apple Inc.'s new iPhone went on sale in stores across the globe Friday, with fans snapping up the final gadget unveiled during Steve Jobs' lifetime, many buying the smartphone as a tribute to the former Apple boss.

Here are five features which have become the attraction of the new smartphone.

iOS 5: The new operating system for the iPhone, which is called iOS 5, has been released by Apple and comes with more than 200 new features such as the iMessage, PC-Free Setup and Twitter Integration.

iCloud: The iCloud service is integrated into some key aspects of the iOS 5 - photos, e-books, device backups, document storage and, of course, the iTunes music program. The most popular iCloud-powered feature amongst users could well be the PhotoStream, an option that can be toggled on or off and which allows users to automatically synchronize photos across multiple devices.

Siri: Siri is touted as an intelligent assistant that helps you get things done just by asking. Siri understands the context, allowing you to speak naturally when you ask it questions, says Apple. Siri is also claimed to be smart about using the personal information you let it access. It helps you make calls, send text messages or e-mail, schedule meetings and reminders, make notes, search the Internet, find local businesses and get directions.

Processor: iPhone 4S has significant hardware upgrades, even though it looks identical to iPhone 4. iPhone 4S is powered by a dual-core A5 chip, which also has dual-core graphics capabilities.

Camera: It has an 8-megapixel camera capable of capturing 1080p video footage.