Donald Trump's first year in office has been a gripping spectacle of scandal, controversy and polarization that has utterly transformed the way Americans and their president interact.

'Welcome back to the studio,' said a beaming Trump, inviting White House reporters into the Cabinet Room for a recap of his first year in office.

It was a lighthearted remark, but a revealing one. For a year now, the world has watched enthralled, and sometimes aghast, at the Trump Show.

Time flies: US President Donald Trump entered office after shattering conventions with his bombastic style

More than any single policy, it's the style of performance that has captivated and, at times, repulsed the world.

'Donald Trump's rhetoric is unlike any president in the modern presidency,' said Richard Vatz, a professor from Towson University, who focuses on presidential communication.

'He communicates more frequently and is less concerned about consistency and consequences from his language than any president in this era.'

He has described himself as a 'very stable genius,' called other countries 's***holes' and repeatedly threatened his political foes.

Many presidents have tried to bypass a critical media - from Franklin Roosevelt's fireside chats to Barack Obama's interviews with YouTubers. But Trump has taken that into overdrive on Twitter.

From one day to the next, he is rarely out of the headlines or off the air, permeating every facet of public life.

Trumpisms like 'many people are saying' have entered the vernacular 'big league.'

Supporters love his no-nonsense style, while opponents are sent into spasms of anger with each new moral outrage, real or perceived.

'Are you not entertained?'

A life-long showman, he has given weighty geopolitical decisions - like his verdict on the Iran nuclear deal or the status of Jerusalem - a tease worthy of a season finale.

He discusses his 'ratings' and media coverage more than almost any other topic.

His pronouncements have come to be taken with a pinch of salt, whether about the size of his inauguration crowd or whether he really does intend to go through with his pledge to pull the US out of the Paris climate accord.

Former Middle East negotiator Aaron David Miller said the gap between the president's words and the reality seen by the rest of the world is a problem.

'The question becomes for our allies and adversaries: how reliable and credible is the president? Does he mean what he says and does he say what he means?' Miller said.

As president, Trump has tweeted more than 180 times about 'Fake News,' and around 170 times alone about Fox News, which offers him gushing praise and, aides say, an emotional crutch.

Despite the braggadocio, the 71-year-old has often appeared more comfortable acting the role of president, rather than carrying out its functions.

In the early months, he frequently led guests across the White House into the Oval Office on a whim, expressing almost as much amazement as his visitors.

While most presidential candidates appeal to the base and then try to broaden their appeal in office, Trump has stuck to a base-first strategy and largely disregarded how his statements are perceived around the world.

Nonplussed Washington diplomats take notes at meetings with journalists, rather than the other way round.

Leaders like China's Xi Jinping, Japan's Shinzo Abe and Russia's Vladimir Putin have found flattery to be the best strategy.

Others have reluctantly followed suit. Leaders from Britain to Norway have come to the White House with praise, at times looking about as comfortable as a medieval prisoner on the rack.

All business

As the White House tells it, at home, the last year has been a festival of legislative achievements and stock market boom.

Wall Street has posted a string of record highs on the back of Trump's business-friendly tax reforms.

How will audiences respond to Season Two of the 'Trump Show?'

But Trump's first year has challenged two decades-old beliefs that made Trump's rise possible: businessmen are more competent than bureaucrats and regular or garden-variety politicians are in it for themselves.

For much of the year, the White House has had a pit-of-vipers quality to it. The 'globalists' leaked against the 'populists' and vice versa. And both leaked against the president.

With John Kelly's arrival as chief of staff and the defenestration of controversial chief strategist Steve Bannon, that back-biting has ebbed.

But chaos remains. Staffers come into work months after being fired. Each week features a fresh departure.

Persistent questions about Trump's conduct have taken a toll. A recent Quinnipiac poll showed 69 per cent of voters think he is not level-headed and 57 per cent that he is not fit to serve as president.

But the Republican-controlled Congress has ensured that political consequences have been limited and Trump remains defiant.

'He refuses to ever apologize and uses his brusque style without apology,' said Vatz.

That may change if investigator Robert Mueller finds evidence that Trump obstructed justice, conducted shady financial dealings or his campaign worked hand-in-glove with Russia -- or if Democrats win control of the Congress in November elections.

But, perhaps more worrying for the showman-in-chief, there may be initial signs that the public is tiring of the drama and beginning to tune out.

According to Google Trends, which logs search data, interest in 'Trump' has waned steadily since he was sworn in last January and now stands 75 percent lower than that high.

High ratings for the second season of the Trump presidency are not assured.