When you sync your iPhone or iPod touch using iTunes, some of your content is backed up on your computer. You cannot edit this backup or sync it with other applications or services, or with non–iPhone OS devices.
This article outlines how to enable syncing in iTunes to transfer content between your device and computer. In addition to creating a backup, syncing with your computer allows you to manage contacts, calendars, and bookmarks on your computer. If you are already syncing your content with MobileMe on your computer or another iPhone, you can sync the data from MobileMe to your iPhone by following the steps in this article.
Learn more about backups.

For help with contacting the iPod or iPhone software update server for Windows Vista, click here.
Some customers may notice the following alert message when trying to update or restore an iPod in iTunes 7 or later:
"iTunes could not contact the iPod software update server because you are not connected to the Internet. Make sure your Internet connection is active and try again."

 
If restoring an iPhone, you may notice this alert message:
"iTunes could not contact the iPhone software update server because you are not connected to the Internet.  Make sure your Internet connection is active and try again."
Internet access is required to download iPod and iPhone software updates. However, if you are able to connect to the Internet with Internet Explorer and can also access the iTunes Store, see the solution below to resolve this issue.

This article outlines some tips and tricks when using Voice Control on iPhone 3GS and iPod touch (Late 2009).

If your device is not recognized in iTunes on a Mac, the Apple Mobile Device Service may need to be removed and reinstalled. These steps may resolve issues with the following devices:

iPhone
iPod touch
iPod nano (5th generation)

This document is for Mac OS X. See this article if you have Windows XP or Windows Vista.

This document is for Windows XP. Click the appropriate link below if you have a different operating system.

Windows Vista or Windows 7
Mac OS X

When the iPhone or iPod touch is connected to Windows XP, a dialog is presented with choices for connecting as a digital camera and working with the digital pictures stored on the device.
This is the default behavior under Windows XP for digital imaging devices. Windows provides a way to disable this notification on a per-device basis.