Use our world or create a new one?

A new world within our world^^

that depends on the story, i like to place mine in old japan. the thing i always do for my story is place it in this world in another place and another time

If I wirte a story, I will sometimes write about my world but I will put I twist to it. Or I write about I life that I wish I had or lived in, like my fantsy dream world. It depends on what your writing about. :)

totally create a new one :P

Usually, make a new world, but it really depends on the story. Like, for instance, The Inheritance Trilogy and Harry Potter had their own "worlds". Could you imagine dragons and dementors flying around in our world? It wouldn't have worked, so the authors made up new ones. The Mortal Instruments takes place in our world because the story called for it. It just depends on what you're writing about.