How to Sort the Contacts on Your iPhone
You can sort the contacts you have stored on your iPhone alphabetically — either by their last names or their first names. Choosing which method to sort your contacts allows you to find people quicker, based on whichever sorting method you prefer.
Tap Mail, Contacts, Calendars, scroll down to the Contacts section, and peek at Sort Order. Then tap Last, First or First, Last.
You can also determine whether you want to display a first name or last name first. Tap Display Order and then choose First, Last, or Last, First.

iPhone 4S Glossary
FaceTime
Apple software that enables users with supported mobile devices to both see and hear each other during wireless conversations.

iPhone 4S Glossary
iCal
Apple’s personal calendar application.

iPhone 4S Glossary
iCloud
Apple’s wireless storage and synchronization service that keeps digital information updated automatically and wirelessly without user instigation.

iPhone 4S Glossary
iOS 5
The operating system for mobile Apple devices released in June, 2011. With iOS 5, data updates and synchronization occur wirelessly through the iCloud.

iPhone 4S Glossary
jailbreak
Altering an electronic device to remove default restrictions imposed by the manufacturer.

iPhone 4S Glossary
Siri
A voice-controlled personal assistant application purchased by Apple and available exclusively on the iPhone 4S.