What is Google Sync?
Google Sync is truly amazing. Basically, imagine if all the important stuff (e.g., contacts, calendars, apps, etc) stored in your Google online account and mobile phone could be merged together and stored on a server---the Cloud as they say. It remains there and continues to be updated always staying in sync with each other. Then if you ever need it (let's say you lose your phone or buy a new one) it self installs in your new phone.
Here is how I got blown away. I bought my phone, plugged in the SIM card and started playing with the menus. Eventually I added my contacts from my previous phone (stored on my SIM card). After some time, I put the phone down with Sync settings turned on. Later when I picked it up again, I found that the phone now had all my contact info from my Gmail account too---imagine all my email addresses which I never bothered to enter on my previous phone's contact list now at my mobile finger tips!
Then when I checked my Google account online, I suddenly saw all my mobile phone contacts (over 1,000) now stored in my Google account.
Never Lose Data Again
So I now have a master set of contact, calendar, and apps I installed in the Google Cloud. And I can pull it into any Android device whenever I need it.
To learn more click Watch Google Sync Video.