Short answers, pulled from the story.
A ghostwriter is a person hired to write literary or journalistic works, speeches, or other texts that are credited to another person as the author. Celebrities, executives, participants in timely news stories, and political leaders often hire ghostwriters to draft or edit autobiographies, memoirs, magazine articles, or other written material.
John F. Kennedy had his book Profiles in Courage almost entirely credited to ghostwriters. Donald Trump's autobiography Trump: The Art of the Deal was produced by a ghostwriter. Nelson Mandela's autobiography Long Walk to Freedom was also produced by a ghostwriter. Several of Hillary Clinton's books were produced by ghostwriters.
In 2013, literary agent Madeleine Morel stated that the average ghostwriter's advance for work for major book publishers was between $40,000 and $70,000. Manhattan Literary states that shorter book projects tailored to new markets start at a cost of $15,000. In 2001, The New York Times stated that the fee for the ghostwriter for Hillary Clinton's memoirs would probably be about $500,000 of her book's $8 million advance.
A music ghostwriter is a person who composes music for another composer but is not credited on the cue sheet or in the final product in any way. David Raksin worked as music ghostwriter and orchestrator for Charlie Chaplin while Wolfgang Amadeus Mozart was paid to ghostwrite music for wealthy patrons. Darryl Neudorf filed a lawsuit against Sarah McLachlan in 1993 alleging he made an uncredited contribution to songwriting on Touch.
Ghostwriting is not illegal in the United States, United Kingdom and Germany although it is considered academic dishonesty if detected by universities. Medical ghostwriting may violate American laws prohibiting off-label promotion by drug manufacturers as well as anti-kickback provisions within the statutes governing Medicare. The European Medical Writers Association have published guidelines which aim to ensure professional medical writers carry out this role in an ethical and responsible manner.