American writer Michael Wolff's upcoming book on the Trump presidency has soared to No. 1 on Amazon.com's best-selling books list, days before it is due to be released on Jan 9.

Excerpts of the book - Fire And Fury: Inside The Trump White House - were reported extensively by US media, sparking a public rift between President Donald Trump and his former chief strategist Steven Bannon.

Here are six things about the 64-year-old Wolff:

1. Who is he?

Wolff is a regular columnist for USA Today, Vanity Fair, Hollywood Reporter, British GQ, New York Magazine and the Guardian, according to his Twitter profile.

Based in New York City, he is also the founder of Newser, a news aggregation website that was started in late 2007.

He was married to lawyer Alison Anthoine, but the couple began divorce proceedings in 2009. They have three children.

That year, he started dating freelance writer Victoria Floethe, 36. Floethe was formerly an intern at Vanity Fair, where Wolff was contributing editor.

2. What is his latest book about?

Fire And Fury: Inside The Trump White House has been touted as the "first tell-all of the Trump presidency" by CNN.

It was written after Wolff conducted 200 interviews and spent several months in the White House at the start of the Trump administration.

In the book, Trump is depicted as presiding over a chaotic White House, struggling to settle into his new reality and eagerly trying to maintain his normal golf habits.

The book's publisher is Henry Holt & Company.

3. His other works

Wolff is the author of six other books, including a biography on media mogul Rupert Murdoch titled The Man Who Owns The News.

The book, published in 2009, was based on nine months of conversation with Murdoch.

In 1998, he wrote the bestseller Burn Rate, which tells the story of the rise and fall of the early search engine company he founded in the early 1990s.

4. He is no stranger to controversies

Wolff has ruffled a few feathers throughout his career. Just before The Man Who Owns the News was published, Murdoch reportedly took issue with parts of the book, where he was supposedly painted in an unflattering light.

In November 2016, Wolff said in an interview with the Digiday podcast that a significant part of a journalist's job is to simply be "stenographers" by relaying what is said to the public and nothing more.

His critique, directed at journalists covering the US presidential election, received strong backlash online.

In February 2017, he criticised the media in an interview with CNN for "having a nervous breakdown" while covering Trump.

Already, Wolff has attracted comments that some quotes in his book were fabricated. For instance, he wrote that Thomas Barrack Jr, a billionaire friend of Trump's, told a friend that Trump is "not only crazy, he's stupid."

But Barrack, speaking to The New York Times on Wednesday (Jan 3), denied ever saying such a thing.

5. His awards and accolades

Wolff has received two National Magazine Awards and four nominations, according to his profile on Newser.

One of the awards was for a series of columns he wrote while in the Persian Gulf at the start of the Iraq War in 2003.

The awards recognise excellence in the magazine industry in both print and digital mediums.

6. He was the editor of Adweek - briefly

Wolff left his post as editorial director of media trade magazine Adweek in October 2011, less than a year after his appointment was announced.

During his stint, he tried to gear the publication towards more consumer-facing media coverage, but the move was met with some doubts.

Sources: The New York Times, CNN, Adweek.com, Newser