Public & Private AS Numbers

Can somebody please explain the advantage of using public AS number instead of private, in BGP??

You can not be multihomed with a private ASN, you must have a public one.

Thanks novembre for info.
But i need to understand it more clearly.
So lets take a case.

"Lets say i am providing service support to any client, and we have the dedicated links from my data center to client data center and BGP running on IPLC routers, then what difference would be there, if migrate the ASN to public from private"

And one more question, "Do we need to acquire the public ASN from some organisation or say from our telecom SP?"

Thanks!

If the client only connects to only one SP then it makes no difference, only matters if the client is multihomed. ASN's are allocated by your local registrar.

I am registering my AS number with ARIN.