Q: how to read summary page in itunes

Hello LAS97,

It sounds like you are seeing "other" data in iTunes when your iPhone is connected.  Sometimes "other" is being used by information like contacts, calendars, the iOS software installed on your device, settings, and other system resources.  I recommend reviewing the following articles to learn more about storage capacity on your iPhone:

Understanding capacity on iPhone, iPad, and iPod

http://support.apple.com/kb/HT1867

How OS X and iOS report storage capacity

http://support.apple.com/kb/TS2419

If you are still seeing more "other" data than expected, it may be that the iPhone was disconnected during syncing:

In the case of iOS device becoming physically disconnected in the middle of syncing music, podcasts, videos or photos, it's possible that orphaned files will be left on the iOS device. This can prevent iTunes from syncing the iOS device on subsequent sync sessions.

One symptom of this issue will be displayed in iTunes where the Capacity indicator for the iOS device will report a large amount of "Other" disk usage for the device. To resolve this issue:

You can find more information and steps to resolve this issue at the following link:

iOS: 'Not enough free space' alert when trying to sync

http://support.apple.com/kb/TS1503

Thank you for using Apple Support Communities.

Best,

Sheila M.