The former president now makes the case for his "friend" Joe Biden.

"Twelve years ago, when I began my search for a vice-president, I didn’t know I’d end up finding a brother," Obama says. "Joe’s a man who learned – early on – to treat every person he meets with respect and dignity."

He continues: "That empathy, that decency, the belief that everybody counts – that's who Joe is."

With vice-presidential pick Kamala Harris, Biden "will restore our standing in the world."

"More than anything, what I know about Joe and Kamala is that they actually care about every American. And they care deeply about this democracy."

Image source, Getty Images

Joe Biden's former boss is streaming in live from Philadelphia, Pennsylvania, turning his fire on his successor: Donald Trump.

"I never expected that my successor would embrace my vision or continue my policies," he says. "I did hope for the sake of our country, that Donald Trump might show some interest in taking the job seriously. But he never did."

"For close to four years now he has shown no interest in putting in the work, no interest in finding common ground, no interest in using the awesome power of his office to help anyone but himself and his friends. No interest in treating the presidency as anything but one more reality show that he can use to get the attention he craves."

As Democrats tout their gun control, immigration reform and women's representation agenda, Republicans are responding with criticisms in real time on social media.

As Hillary Clinton delivered her speech, Ronna McDaniel, the Republican chairwoman, mocked the former candidate, tweeting that she "still can't get over her loss in 2016".

The Democrats' immigration plan is rich, suggested Charlie Kirk, founder of the conservative group Turning Point USA.

"Barack Obama was known as the 'Deporter-In-Chief' during his time in office," he tweeted. "Interesting how the Democrats are conveniently forgetting that tonight".

The former president will speak later tonight, and is expected to issue a pointed criticism of his successor Donald Trump, and endorse Biden, his former vice-president.

Ann Coulter, a well-known right-wing commentator, let a picture say what she thinks of his speech:

As we wait for remarks from former President Barack Obama, video shows a highlight (featuring some tears) in the close friendship between Obama and his former Vice-President Joe Biden.

Image source, DNC

Well-loved by the party's left-wing, Elizabeth Warren was an early frontrunner in the 2020 race, and the first major Democrat to announce her bid. Though she was known as the candidate with a plan for everything, her initial momentum tapered off, resulting in a poor showing during the biggest primary elections.

She sparred with Joe Biden over heathcare during the debates (Warren supports her fellow progressive Bernie Sanders' Medicare for All single-payer system plan), but eventually endorsed him in April - the last of his 2020 Democratic rivals to do so.

Tonight, she has turned out to support former rival Biden.

"I love a good plan," she says, echoing her own 2020 presidential campaign slogan. "And Joe Biden has some really good plans."

Warren turns to a plan especially close to her heart - and her aborted 2020 candidacy - childcare. "The thing that almost sank me," she says. "Joe and Kamala will make childcare affordable to every family," Warren says, urging Democrats to turn out.

Where did it go wrong for Elizabeth Warren?

Laura Trevelyan
Presenter, BBC World News America

The Democrats seem to want to build a wave of activism by women. Nancy Pelosi talked about a record number of women in the House of Representatives in the Democratic Party. Clearly there is an attempt going on to harness the power and the energy of women on the Democratic side, to try to win the presidency and the Senate and to increase the majority in the House of Representatives.

Anthony Zurcher
BBC North America reporter

The Democrats just ran a video touting the Violence Against Women Act, a piece of legislation – as they note - that Joe Biden worked for years to get passed. Interestingly enough, the way he finally got it made into law was by attaching it as an amendment to the Crime Bill of 1994. That bill included mandatory minimum sentences and prison construction that many Democrats now view as leading to an epidemic of mass incarceration that adversely affected African-Americans.

One of the tricky things about being a legislator who runs for president is that successes in Congress require a lot of compromises, some of which can later prove to be politically harmful.

Image source, DNC

Pelosi continues to give a fiery rallying call, and continues to rebuke the President Trump.

"We will remember in November when we will elect Joe Biden president, whose heart is full of love for America, and rid the country of Trump's heartless disregard for America's goodness," Pelosi says.

"Joe Biden is the president we need right now - battle tested, forward looking, honest and authentic. He has never forgotten who he is fighting for.

"And Kamala Harris is the vice-president we need right now, commited to our Constitution, brilliant in defending it and a witness to the women of this nation that our voices will be heard."

Now, it's time for the third most powerful politician in Washington to have her say: Speaker of the House of Representatives, Nancy Pelosi.

She's a political powerhouse whose been in the business since 1976. The first woman Speaker of the House, she's been the face of the opposition to the White House on Capitol Hill, and hasn't shied away from sharp critiques of Donald Trump's leadership, accusing him of lies and temper tantrums - and once famously ripping up his State of the Union speech on national television.

"Our diversity is our strength, our unity is our power," Pelosi begins.

"This month, as America marks the centennial of women finally winning the right to vote, we do so with 105 women in the House. Proudly, 90 are Democrats."

She highlights Democratic House efforts on police reform; gun violence; immigration and climate change.

"As Speaker of the House, I've seen first hand Donald Trump's disrespect for facts, for working families and for women in particular. Disrespect written into his policies toward our health and our rights, not just his conduct."

Nancy Pelosi: The remarkable comeback of America's most powerful woman

The former Secretary of State picks up on a big theme running through the convention: the urgent need to vote.

"If Trump is re-elected things will get even worse," Hillary Clinton says.

"Remember back in 2016 when Trump asked what do you have to lose? Well, now we know. Our health care, our jobs, our loved ones."

Clinton turns her focus to the Democrats leading the 2020 ticket: "Let's set our sights higher than getting one man out of the White House. Joe Biden and Kamala Harris are going to give us so much to vote for."

Anthony Zurcher
BBC North America reporter

As the Democratic convention rolls on through its third night, some of the kinks from the first few evenings appear to be ironed out and the production levels are getting better.

The video of Joe Biden taking the phone and talking with a campaign intern’s grandmother, for instance, was a clever way to highlight the candidate’s empathy – and, perhaps, draw a contrast with the current occupant of the White House.

A virtual convention like this was always going to have a sharp learning curve for organisers. Nothing quite like this has ever been done before, and many of the participants are much more comfortable talking to crowds then they are staring at a camera in an empty room.

The make or break moment, of course, will come when Biden himself speaks Thursday night. Everything done up to that point can help set the stage - or create additional obstacles - but in the end it’s up to the candidate to deliver.

Image source, Getty Images

Hillary Clinton - the Democratic nominee from the last time around - is taking on Donald Trump head-on.

"When I said we owe Donald Trump an open mind and a chance to lead, I meant it," she says, recalling her remarks the day after she lost the election to Trump. And "if he had put his own interests and ego aside" things may have been different.

"I wish Donald Trump new how to be a president. America needs a president right now," she says. "We need Joe Biden and Kamala Harris."

President Trump posted his response hours before the event began.

Anthony Zurcher
BBC North America reporter

Image source, Getty Images

In an alternate universe, Hillary Clinton isn’t giving an 'I-told-you-so speech' at this Democratic convention, she’s being re-nominated by her party for a second presidential term.

At least, that thought could be going through the former secretary of state’s mind as she addresses her party faithful via remote broadcast. It is certainly what more than a few Democrats have been thinking, as well – wondering what might have been.

After all, Clinton won millions more votes than Donald Trump in 2016, and a shift of fewer than 80,000 votes in three states - Pennsylvania, Michigan and Wisconsin - would have delivered her an Electoral College victory.

Instead of a virtual balloon drop in her honour, however, Clinton is left lamenting that people tell her they wish they could “go back and do it over” and warning that this can’t be another “woulda coulda shoulda election”.

Instead of being the first female president in American history, she is - for Democrats - a cautionary tale, a haunting ghost of elections past.

Barbara Plett Usher
BBC News, Washington

The Biden administration has a plan it says will restore American leadership and a promise to reverse the unilateralist instincts of President Donald Trump. On day one of a Joe Biden presidency, the US would re-enter the Paris Climate Agreement, rejoin the World Health Organisation and seek to lead a global coronavirus response, he says.

Republican analysts counter that this would be more style than substance. They argue that the Trump administration has engaged the world, just with sharp elbows. Soothing the bruises inflicted on allies would be at the top of the Biden priority list, even if some core policy demands – such as pressure for Nato members to spend 2% of GDP on defence – stayed the same.

There would be 180-degree policy turns: an aggressive focus on addressing climate change, an increase in refugee admissions, and a reversal of the travel ban on people from some Muslim majority countries.

Biden would re-enter the Iran nuclear agreement if Tehran resumed its commitments to nuclear limits – but he hasn’t promised to lift the sanctions imposed by the Trump administration after it withdrew from the deal. He has said he’d end US support for the Saudi-led war in Yemen, which began under President Barack Obama. On Russia, the relationship at the top would change - but likely little else.

Like Trump, Biden would counter China’s “abusive economic practices,” though jointly with allies, instead of through proposed unilateral trade deals. The Trump administration's sharp elbows have been successful in winning global support for a boycott of Chinese communications technology, but Biden would more likely actively seek areas of cooperation with a rising China, similar to the approach of President Obama.

Image source, Getty Images

Peyton Forte, 21, is a recent graduate. She tells the BBC what she expects ahead of vice-presidential pick Kamala Harris's address tonight.

"I think her speech will provide a huge boost to the Biden campaign. Senator Harris has never held back in her criticisms of Donald Trump and I expect her speech to be centred upon her abilities as a leader to guide America through this difficult time, especially in areas where the current administration has failed, like the Covid-19 response, tensions with China, Russian election interference.

"I expect for people to compare her speech with Michelle Obama’s, but comparisons and a lack of opportunity for individualism come with the territory of being prominent black women in politics."

Read from more young black voters on what they think of Kamala Harris as Joe Biden's running mate.

Anthony Zurcher
BBC North America reporter

New Mexico Governor Michelle Lujan Grisham, who was reportedly under consideration to be Joe Biden’s running mate, is the most prominent Hispanic politician to address the Democratic Convention this week.

In fact, Democrats have received some criticism for having too few of this key demographic on the virtual stage. Julian Castro, for instance, was the only Hispanic to run for president this year, but he didn’t receive a speaking slot.

Democrats will need the strong support of Hispanic voters if they want to win key electoral battleground states like Arizona and Florida in November and, perhaps, put a big, traditionally conservative prize like Texas in play.

Image source, Getty Images

And it's quickly onward to the next hot topic on the Democratic agenda: immigration.

"Etched into the DNA of who we are as a nation is the very idea that though you may be from somewhere else, you can find your home here," says our host, Kerry Washington, describing her own family's immigrant past.

"But now that idea is in danger, more than ever before."

We’ve seen some of the starkest political divides on this issue - particularly under President Trump’s tenure.

It's a topic Trump often uses to fire up his conservative base - you may recall the rally chants of “build the wall” - and immigration has remained a key part of Trump’s America First platform.

In his 2020 campaigning, Trump has sought to cast the Democrats as the party of open borders, touting the 300 miles of progress he's made on his US-Mexico wall.

A 2019 study found that Democrats have more favourable views of immigrants than Republicans - but since 2016, the overall view that immigrants strengthen American society is up 11 points to 57%, across both parties.

Laura Trevelyan
Presenter, BBC World News America

Image source, Getty Images

Kamala Harris’ surprise appearance at the opening of tonight’s proceedings served to underline a central theme of the week - the importance of making a plan to vote.

Michelle Obama on Monday, wearing a necklace that spelled 'Vote', urged Americans to pack a bag and stand in line for as long as it takes to cast a ballot.

With concerns about how long it will take to vote in person in the era of coronavirus, and the ongoing political row over the US postal service and whether it has the capacity to process millions of postal votes - Democrats are encouraging people to make a plan, knowing that some 80,000 votes were the difference between Hillary Clinton allowing and Donald Trump winning in 2016.

Early voting in some states begins in September.

Image source, Getty Images

Pop star Billie Eilish appears for a virtual performance in support of the Biden/Harris ticket. "You don't need me to tell you things are a mess," she says. We do need her to sing though, and she duly obliges.

The performance comes just a couple of months before a major milestone for the Grammy Winner: the first presidential election in which she'll be eligible to vote.

The 18-year-old is part of Generation Z - those 18 to 23 - a group that will compromise about 1 in 10 of eligible voters in the US this fall, up from just 4% in 2016, when the vast majority were too young to cast ballots.

This group is racially and ethnically diverse, and similar to Millennials a generation above them, Gen Zers are seen as progressive and pro-government.

And those in Eilish's cohort - coming of age amid a pandemic and a looming recession - are less likely than older generations to see the US as superior to other nations, according to the Pew Research Center.

Image source, Getty Images

In his platform, Joe Biden has vowed to get the US back in the Paris accord, in addition to a sweeping $2 trillion climate and energy plan. The Democratic candidate has also committed to reaching 100% “clean energy economy” by 2050 and has described climate change as “the challenge that’s going to define our American future”.

It would be a major U-turn after four years of Donald Trump in the White House. Since he assumed office, Trump has rolled back hundreds of environmental protections, including limits on carbon dioxide emissions from power plants and vehicles, and protections for federal waterways across the country, fulfilling a campaign promise from 2016. He withdrew the US from the Paris climate agreement, saying the deal disadvantaged the US “to the exclusive benefit of other countries”.