Understanding BCP and Format Files

I'm in the process of familiarizing myself with the format file option (-f) with the BCP command.  I'm failing to grasp the advantage of referencing format file with the BCP in (import) or BCP out (export) options.  With an import, either you have a correctly formatted import file and BCP command or you don't.  Right?  With an export file, your export is going to be the same whether you reference the format file or not.  Right?  Clearly, I'm missing the boat on the -f option, but I'm not sure how.  

I've been reading the following article: http://msdn.microsoft.com/en-us/library/ms191516.aspxStart Free Trial