Guild wars eye of the north, what is it?

i just recently finished guild wars nightfall, i want to get eotn but i dont really understand what it is....do u play with existing characters from other campaigns? if so, how?Guild wars eye of the north, what is it?
Eye of the north is the expansion pack. You go to tyria, the land in guild wars prophecies, but a lot of land is cut off because you need prophecies to go there. Places like Kryta and ascalon. Anyway you can play any of your characters from all three campaigns in eye of the north. But as i said before, if you play nightfall or factions without prophecies, the land is limited. So i would recommend you get prophecies aswell if you have enough money.Guild wars eye of the north, what is it?
Yup same Character

In any Campagin

I think You need the original guild wars tho

Good luck

Btw it ells you in the Gwen (Guild wars: Eye Of the north) Instruction Booklet how to use It