Every iPhone and Android user should do this simple method of syncing their contacts to a Gmail account. Not only is it another backup for all your contacts and calendar events, but having a Google account opens up another world of services to you that is not only free but ever expanding with new features. This is the iPhone version.
The best way to get started is to create a free Gmail account. If you don’t have one, go to gmail.com and click the red CREATE AN ACCOUNT at the top right corner.
Now adding the account to your device is very simple.
STEP 1 – Touch the SETTINGS button
STEP 2 – Touch Mail, Contacts, Calendars
STEP 3 – Touch add account
STEP 4 – Touch Microsoft Exchange, not Google Mail
STEP 5 – Enter your Gmail info
Email is your full Gmail
Leave the Domain blank,
Username is your full Gmail again,
Password is your Gmail password,
Touch Next,
STEP 6 – Enter Server info,
now the screen should change and there will be a new box for Server info
Server is m.google.com,
the rest of your info typed in previous step stays
Touch Next, you should see check marks by all your entries indicating successful login,
then you should see this screen,
be sure to turn off Mail, leave Contacts and Calendars on.
If you already have contacts on your phone, you will want to touch, Keep on My iPhone
Your done. Now you can also login to your Gmail and see the contacts from your device on the web.
Anything you add on the web or on your iPhone will sync both ways. You will see the convenience of this automatic sync immediately. Imagine if you spent a whole afternoon adding important numbers and then losing your phone before you got home and synced with iTunes. With this sync in place you could still access all the numbers as soon as you login to your Gmail.
For more details see this link on the Google site.