A publishing contract is a legal contract often entered into by a writer and a publisher who has chosen to publish a specific book. Often literary agents and attorneys are hired by authors in order to secure a publishing contract and negotiate the terms of the contract. A publishing contract generally contains specific information about a variety of issues related to the publishing process, including how a book will be edited, published and marketed, subsidiary rights such as movie rights or audio book rights, who retains the copyright to the book, and how an author will be paid. Both advance payments and royalties are common in publishing contracts. Royalties are percentages of book sales, while advances are paid out before a book is completed, and may be paid when authors reach certain milestones. Some publishers attempt to convince authors into signing bad contracts by using attractive advances to lure them in. As with any legal contract, an author should consider consulting an attorney before signing a publishing contract to make sure the contract is in their best interest.