Newspapers, whether daily or weekly, contain news articles, as well as reviews of books, music and music concerts, and theater productions, and opinion pieces (editorials or guest commentary), business and finance news, and sports. They also may interview book authors, playwrights, poets and musicians. Letters to the editor from readers may also be published. Newspapers provide the first accounts of events, often written by staff journalists on a deadline. Some articles and commentary might also be written by free-lance writers, who are not on staff, but are paid for the individual article.. Newspapers are not peer-reviewed journals but some news stories may mention and explain to the general newspaper readership about peer-reviewed studies.