In 1968, there were intense arguments at the Democratic convention over the Vietnam War. But the bigger news happened outside the convention hall. Several thousand war protesters battled with police, and dozens on both sides were injured.
In the past 40 years, conventions have had very little drama. There are usually a few dozen speakers to rally the delegates - and the TV viewers - around the nominee. There are votes on the party's platform, or priorities. And on the final day, the nominees give an acceptance speech that reveals what they believe about important issues.
But this year seems to be different. Clinton opponent Sen. Bernie Sanders hasn't officially given up his campaign. He wants the Democratic Party to support his ideas. And Trump has made comments that have turned some in the Republican Party against him.
So tune in and see for yourself how these disagreements are resolved. But also try to spot the funny hats.
Words to know
• Delegates: Party members representing each state, Washington, D.C., and U.S. territories who choose the candidate.
• DNC: Democratic National Committee, the governing body of the Democratic Party.
• Keynote: The most important speech at the convention, other than the nominee's speech.
• Nominee: The candidate the party chooses to run for president.
• Platform: The party's position on various issues.
• RNC: Republican National Committee, the governing body of the Republican Party.