It's a tradition dating back to the 1830s, when a group of Democratic delegates supporting President Andrew Jackson gathered in Baltimore to nominate him for a second term.
This year will look slightly different from others, as the party has already officially nominated Vice-President Kamala Harris in a virtual roll call after President Joe Biden dropped out of the race.
But many of the other DNC traditions - including appearances from celebrities and memorable speeches from party leaders - will remain the same. Here’s what to know.
When and where is the DNC?
This year’s convention is taking place at the United Center Arena in Chicago from Monday 19 August to Thursday 22 August.
What happens at the DNC?
Because Ms Harris and Mr Walz have already been nominated, this year's convention will focus on speeches from prominent Democrats and the adoption of the party’s platform.
Delegates work during the day to finalise the platform, a draft of which has already been released.
It focuses on a broad range of issues, including plans to lower inflation, mitigate climate change and tackle gun violence. In the draft, Democrats contrast each of the party positions with Project 2025, an ultra-conservative blueprint for what a second Trump administration could look like, authored by the Heritage Foundation. Trump has sought to distance himself from the project, though several of his allies were involved in writing it.
Who will be speaking?
Dozens of prominent Democrats and celebrities will be taking the stage in Chicago.
President Biden will headline the convention on Monday night, and his record will be honoured throughout the evening.
The crowd will also hear from First Lady Jill Biden, former Secretary of State Hillary Clinton, Maryland Rep Jamie Raskin, Chicago Mayor Brandon Johnson and other Democratic leaders. Americans affected by abortion bans in Republican-controlled states and voices from the labour movement - including United Auto Workers President Shawn Fain - will be heard as well.
The first evening of the DNC will "showcase Kamala Harris’s commitment to fighting for everyday Americans" with a particular focus on "freedom", DNC officials told reporters.
On Tuesday, former President Barack Obama is expected to deliver remarks, as is former First Lady Michelle Obama. Illinois Governor JB Pritzker and Ms Harris’s husband, Second Gentleman Doug Emhoff, will also address the convention on Tuesday.
Wednesday’s line-up reportedly features former President Bill Clinton and former Speaker of the House Nancy Pelosi, among others.
Ms Harris’s running mate, Minnesota Governor Tim Walz, will give the prime-time speech that night after his nomination.
The most important night of the convention is Thursday, when Vice-President Harris will take the stage. She will formally accept the presidential nomination and give her speech on the final night of the convention dedicated "For the Future".
Former Secretary of State Hillary Clinton, Senate Majority Leader Chuck Schumer and House Minority Leader Hakeem Jeffries will also take the stage at some point during the week.
Famous politicians aren’t the only ones who will make an appearance. The convention will also hear from several everyday Americans, including Trump voters.
Who else will be in attendance?
Around 50,000 people are expected to attend this year's convention in Chicago. This includes thousands of delegates chosen by state Democratic parties as well as super delegates, who are major elected officials, notable members of the Democratic Party and some members of the Democratic National Committee.
Thousands of members of the media will also be in attendance.
It will be a star-studded convention with appearances from several celebrities. In 2020, actors Julia Louis-Dreyfus and Eva Longoria attended the convention, while Elizabeth Banks and America Ferrera appeared in 2016.
Rumours have swirled about whether mega-stars Beyoncé and Taylor Swift will attend this year, but neither has confirmed.
Will there be protests?
Demonstrations are planned for outside the DNC venue, many of which are centred around opposition to US support of Israel’s war in Gaza. Organisers have said as many as 10,000 people could take part in marches. Protesters have been haggling with the city of Chicago about where they can demonstrate.
How can I follow coverage?
Members of the public can only attend the convention in person by becoming volunteers. But as with the Republican convention, there will be plenty of national media coverage, and the convention itself will offer live-streams on social media platforms.
You'll be able to follow BBC News coverage - featuring on-site reporting and analysis - across the website and app, and on our live-stream.
The BBC News Channel will carry special coverage from 20:00 ET (01:00 BST) each night. You can find special episodes of The Global Story and Americast podcasts on BBC Sounds and other podcast platforms.
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Madeline Halpert