But you can follow updates to the story here.

Today's testimony saw both witnesses push back against Republican talking points. Notably, Fiona Hill criticised lawmakers for peddling "fictional narratives" about Ukrainian election meddling.

The president again weighed in during a hearing, commenting on Holmes' statement that he overheard the president's call with Ambassador Gordon Sondland even though the call wasn't on speakerphone.

The hearing also drew attention to ex-National Security Adviser John Bolton, Hill's former boss, who is waiting for a judge to rule about whether he needs to obey Congress's demand to appear.

Want a more in-depth look? We've got you covered.

• Watch: Why Hill got testy with EU ambassador
• Republican claims fact checked
• How the Trump-Ukraine story unfolded
• A bombshell for Trump - our North America reporter's analysis of the hearings

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Democratic Congressman Raja Krishnamoorthi asked about a 2018 radio broadcast by Trump confidant Roger Stone, who was found guilty of lying to Congress last week.

In March 2018, Stone spoke on a conspiracy theory chat show to call Hill a "globalist leftist Soros insider" who was a "mole" in the Trump White House.

Krishnamoorthi asks if she is "leftist" or a "mole" working for left-wing Jewish philanthropist George Soros, as he quotes Stone.

"Leftist maybe," says Hill, adding that "left" has a politically different meaning in Europe.

She also dismisses conspiracy theories involving Soros, calling them part of "the longest running anti-Semitic trope that we have in history".

Democratic Congressman Sean Maloney asks why then-National Security Adviser John Bolton told Hill in July to report to White House lawyers how US officials were placing Ukraine under undue pressure.

Bolton, says Hill, "clearly wanted to have himself on the record as not being part of what was basically an agreement to have a [White House] meeting in exchange for investigation".

Efforts by Sondland, and others, to pressure Ukraine, "was improper and it was inappropriate, and we said that in real time," says Hill.

Hill has testified that Bolton told her he wanted "no part of this drug deal" with Ukraine.

Listening to lawmakers all day can get a bit dull. But Twitter has some ideas about what you should listen to next.

And maybe coming soon:

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A mystery whistleblower, a former comedian and the president of the United States.

These are some of the main players in a story that is becoming ever more complex - and could see the president impeached.

Catch up on who's who here.

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Twitter users have been speculating all day over who would play Fiona Hill in "Impeachment: The Movie".

During earlier impeachment testimony, the same game was being played for other witnesses.

There's a very rich profile of Hill in the New York Times., external

Ms Hill, 54, had an unusual path to academia. The daughter of a coal miner and a midwife, she had a hardscrabble childhood in northeast England - a childhood that bred toughness, her friends say. Once, when she was 11, a boy in her class set one of her pigtails on fire while she was taking a test. She put the fire out with her hands, and finished the test.

She learned to speak Russian and eventually made her way across the Atlantic to Harvard for a fellowship, where she studied under the scholar Richard Pipes, known for his hard-line views about what was then the Soviet Union.

Ms. Hill’s own views are more nuanced, friends and colleagues say; she is not so much a Russia hawk as a cleareyed realist. She was also very clear about the threat Russia posed to Ukraine.

“She comes from this realist tradition where you start with the proposition that this other actor is capable of killing me,” said Graham Allison, a Harvard political scientist who worked with Ms. Hill on an initiative to teach foreign governments about democracy. “I can’t figure out how to kill them without committing suicide, so now I have to find a way to live with them."

Image source, Getty Images

And Hill has since referenced the profile, noting that the hair-on-fire incident had the unfortunate consequence of a bowl cut.

"I looked like Richard III," she said, though some on Twitter have debated the accuracy of the comparison.

Trump is accused of breaking the law by pressuring Ukraine's leader to dig up damaging information on a political rival.

In July, he urged his Ukrainian counterpart to investigate one of the frontrunners for the Democratic nomination in next year's presidential election.

An impeachment inquiry that could see the president eventually removed from office is under way.

But there is a fierce debate about whether Trump broke the law or committed an impeachable offence - he himself says he has done nothing wrong.

Want more detail? Read the full story here.

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Ohio Republican Brad Wenstrup used his time to attack Democrats and question Hill's credibility - without actually asking her any questions.

Hill asks if she can respond anyway, and chairman Adam Schiff allows it.

She says that Wenstrup's remarks about "overcoming hatred and certainly partisan division" were powerful.

"All of us who came here under a legal obligation also felt we had a moral obligation to do so. We came as fact witnesses," she says.

"I don't believe there should be any interference of any kind in our elections."

Hill adds that it was "unfair" for people to attack Trump when he was a candidate too, and knows "it's put a huge cloud over this presidency and our whole democratic system".

And that's why, as a non-partisan Russia expert, she says, she wanted to serve the country.

Hill also says that Trump is right to say that we should improve our relationship with Russia, to stabilise things and "ensure what they did in 2016 doesn't happen in 2020".

"We're here just to provide what we know and what we've heard," Hill concludes, saying that ultimately, it's up to lawmakers to make the tough decisions.

Republican Chris Stewart welcomes the end of "impeach-a-palooza" as he condemns Democratic "crocodile tears".

The "palooza" line refers to the famous "Lollapalooza" music festival that takes place over several days in Chicago each year.

Stewart mocks lawmakers who claim be to "heartbroken to have to impeach this president".

"They're giddy over this," he continues. "Everybody knows whats going to happen next."

"We've all been to a concert. We've got the warm-up act here," says Stewart, calling this weeks' hearings "a band that nobody's ever heard of".

"But the warm-up act is over," he says, calling an impeachment trial in the senate "the main event".

If Trump is impeached by the House of Representatives, he faces trial in the Republican-controlled Senate.

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Senior Ukrainian officials "said some pretty hurtful things about the president", says Hill, adding that they "bet on the wrong horse" by hoping for Hillary Clinton to win in 2016.

They said "pretty disparaging, hurtful things about President Trump and I can't blame him for feeling aggrieved about them", says Hill.

Republicans in the committee have sought to portray the support that some Ukrainian officials had espoused for Clinton as evidence of Ukrainian meddling in the 2016 election.

Terri Sewell, an Alabama Democrat, has asked Fiona Hill a recurring question from these hearings: Are you a Never Trumper?

"I honestly don't know what the definition of a Never Trumper is," Hill says, adding that she thinks many of her colleagues probably feel the same.

"It is a puzzling term to be applied to career or non-partisan officials. And I chose to come into the administration. I could easily have said no when I was approached."

Never Trumper is a term that was originally used to describe Republicans who wanted to prevent Donald Trump from winning their party's presidential nomination.

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US diplomat to Ukraine David Holmes held his hands up earlier, to demonstrate how he was able to hear Trump's voice through Gordon Sondland's personal mobile phone.

"When the president came on, [Sondland] sort of winced and held the phone away from his ear like this," Holmes said gesturing with his hands.

He added: "And he did that for the first couple of exchanges. I don't know if he then turned the volume down, if he got used to it, if the president moderated his volume, I don't know. But that's how I was able to hear."

Holmes says the conversation between Sondland, the US Ambassador to the EU, and Trump then turned to American rapper A$AP Rocky, who was jailed in Sweden at the time. But he could not hear Trump's half of that conversation, he testified.

Image source, Getty Images

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Let's get our heads up for a minute and look at the wider story here.

We’ve made it easy for you.

SIMPLE GUIDE: If you want a basic take on what's going on, this one's for you

GO DEEPER: Here's a 100, 300 and 800-word summary of the story

WHAT'S IMPEACHMENT? It's a political process to remove a president - video guide

VIEW FROM COAL COUNTRY: Hear from residents in West Virginia

ANALYSIS: The 'bombshell' of Sondland testimony

FACT-CHECK: Is the whistleblower linked to the Democrats?

In addition to the politicians, there are two others you should know - the counsel.

Castor has just finished his questions for the Republicans.

Goldman has been asking them for the Democrats.

Republican Devin Nunes asks Fiona Hill about the so-called Steele dossier, which surfaced shortly before the 2016 election. It made unsubstantiated claims about supposed links between the Kremlin and Trump.

These included that Trump was once filmed with prostitutes at a hotel in the Russian capital during a 2013 trip for one of his Miss Universe pageants. Trump denied this.

The dossier was paid for by the Washington DC research firm Fusion GPS, conducted by a former British intelligence officer, Christopher Steele, and funded mainly via a law firm representing the Democratic National Committee and Hillary Clinton's campaign.

Hill just testified that she knew Steele, but that the dossier was "a rabbit hole".

She said she was shown the dossier by one of her colleagues at Washington DC foreign policy think tank the Brookings Institution, Strobe Talbott, a day before it was published in Buzzfeed.

Talbott was deputy secretary of defence under President Bill Clinton. Ironically, Talbott was once himself accused of being a Kremlin dupe, which he denied.

In a new book about the claims written by the operatives at Fusion GPS, they write that "many of the allegations in the dossier have been borne out", though concede that "other details remain stubbornly unconfirmed, while a handful now appear to be doubtful, though not yet disproven".

Read more:

• Trump 'compromising' claims - how did we get here?
• Defamation case against Christopher Steele dismissed
• Dossier key claim 'verified'
• Trump-Putin: Your toolkit to understand the story

US diplomat in Ukraine David Holmes has testified that the so-called black ledger, which documents corruption in Ukraine, is "credible".

The "black ledger" emerged in Ukraine during the US presidential campaign and appeared to show that Trump's now jailed former campaign manager, Paul Manafort, received undeclared payments from a Ukrainian pro-Russian political party.

Some Trump supporters have argued the document must be fake, and was deliberately put out by Ukrainian journalist-turned-politician, Sergei Leschenko, who hates Trump.

In the more than three years since the black ledger emerged, no-one has managed to cast serious doubt on its contents.

Special counsel Robert Mueller’s office did not introduce the black ledger at Manafort’s trial.

Read more about the ledger here: Three Republican claims fact-checked

Image source, g

Image source, Getty Images

"I was a bit rude," towards Sondland, says Hill, describing one of several "testy" encounters she had with him.

She says that she was angry as she asked Sondland who "put him in charge" of Ukraine.

"And he said 'the president', which shut me up."

"I was upset with him that he was not fully telling us about all the meetings he was having," she continues.

But she later realised Sondland "had a different remit".

"He was running a personal domestic political errand we were concerned with national security."

"And those two things had just diverged."

Image source, Getty Images

"As has been the case throughout the Democrats' impeachment sham, today's witnesses rely heavily on their own presumptions, assumptions and opinions," says White House spokeswoman Stephanie Grisham in a new statement.

"These two witnesses, just like the rest, have no personal or direct knowledge regarding why US aid was temporarily withheld.

"The Democrats' are clearly being motivated by a sick hatred for President Trump and their rabid desire to overturn the 2016 election. The American people deserve better."

Anthony Zurcher
BBC North America reporter

Image source, Getty Images

The 10 Democratic presidential candidates on the debate stage in Atlanta, Georgia, last night had a difficult job before them - condemn Trump while also trying to wrest the American public's attention from the ongoing impeachment hearings.

Senator Elizabeth Warren, a front-runner and one of the first candidates to suggest Donald Trump should be impeached, said she would try to convince Republican senators to vote him out.

She added a plug for her anti-corruption plan, which includes a proposal to ban big campaign donors (like EU Ambassador Gordon Sondland) from being named ambassadors.

Senator Bernie Sanders labelled Trump a pathological liar. Indiana Mayor Pete Buttigieg said Trump abused his power but also called for unity - a major theme of his campaign.

Then there was Joe Biden, the man Trump encouraged the Ukrainians to investigate. Although the former vice-president's once dominating lead in the polls has been greatly reduced, he said he attracted Trump's attention because he's the one best positioned to beat him.

Read more about last night's Democratic debate from Anthony