In BGP what is the advantage of using AS Prepend?

AS-PATH prepending is an important tool in BGP toolbox to influence the return traffic back to your networks.AS-PATH prepending changes the way that your advertised prefixes appear to the rest of the Internet. The as-path length is evaluated early on in the path select process so this is a powerful tool to use with BGP. The shorter the AS-PATH the more preferred a prefix becomes. AS-PATH prepending is used to make a route less desirable, along a specific path, by making the AS-PATH longer.