Serial number provides some interesting information about your iPhone, like the week it was manufactured, the factory id and much more.
The first step is to locate the Serial Number. The easiest way to find it is to open your Settings app and navigate to General -> About -> Serial Number. You should also see the Serial Number in the Summary tab in iTunes when your iPhone is connected to the computer.
Serial numbers come in the form AABCCDDDEEF
where
> AA = Factory and machine ID
> B = Year manufactured (simplified to final digit, 2010 is 0, 2011 is 1, etc)
> CC = Week of production
> DDD = Unique identifier
>...
