How do authors get their books published?
Only two methods exist for book publishing: the traditional one of a publisher buying the right to make a book from a manuscript and self-publishing (true, assisted, vanity, subsidy, whatever), which is self-explanatory. Ignoring self-publishing, the path from manuscript to book varies depending on the form (fiction or nonfiction) and the publisher (one that accepts unsolicited manuscripts/queries or only agented mss). Writers who aim for the top publishers generally need to be represented by an agent. Many other publishers will accept unsolicited manuscripts or, at least, queries. The nonfiction books are more often sold from a proposal. Novels need to be a finished manuscript.