The iOS 4.2.1 have been made public by Apple and is now available to download or update. One of the main features of this release is that the taste of iOS 4.2.1 also comes up for the iPad this time. It brings features like folders in iPad, Airplay, Airprint etc. If you want to update iPhone 3G, 3GS or 4 to iOS 4.2.1, here are the steps to do it.

You could update your iPhone to iOS 4.2.1 in two ways : Automatically and Manually.

Updating to iOS 4.2.1 Automatically Via iTunes

1. Download iTunes 10.1 from here.

2. Connect your iPhone to the computer.

3. iTunes shows an iOS 4.2.1 update message.

Update iPhone to iOS 4.2

4. Click the “ Download and Install “ button to update iPhone 3G / 3GS / 4 to iOS 4.2.1.

Updating to iOS 4.2.1 Manually Via iTunes

1. Download iTunes 10.1 from the above link and iOS 4.2.1 IPSW for iPhone from here..

2. Connect your iPhone to the computer.

3. Choose your device from the left sidebar.

4. Press the Shift key(in Windows) or the option key(in Mac OS X), click on the Restore button.

5. Now browse to the iOS 4.2.1 IPSW file and select it.

That’s it! Your iPhone will now be updated to iOS 4.2.1.