Apache mod_rewrite domain to subdomain?

Question

Hello, I have this address http://www.example.com and have this page http://www.example.com/world. Can I do this with mod_rewrite,to my page become http://world.example.com ? Any link,tutorial,...,will be nice,if I can do this? And what will be with these links for example:

  http://www.example.com/world/some-other-page
  http://www.example.com/world/and-second-apge

will these links also be rewritten to :

 http://world.example.com/some-other-page
 http://world.example.com/and-second-apge

Another question,is this good for SEO ?

I'm sorry on my bad English.