How is a book co-authored?

Question

How do two people write a book together? Writing seems like a solitary hobby to me. I can understand two people coming up with a story together, researching together, etc.. But when it comes down to actually writing it, doesn't that really need to be done by just one person?

Answer 1

usually, two authors get together and brainstorm and write together, and try to integrate their writing. sometimes, with people like rachel cohn and david levithan, one author writes every other chapter, or for one specific character.

Answer 2

One person is a charicter, and the other is a writer.  The writer can give the charicter or co author credit instead of stealing his or her works and loosing friendship.

Answer 3

It seems like when you see this, it's someone you've never heard of co-authoring with a very well known author.  I've always thought that the "unknown" person was really the main writer and the well known name is on there so more people will read the book.  Perhaps they've consulted together some?!?