- Feb 4 Mark Zuckerberg launches Facebook from his Harvard dormitory room
- Apr 8 Darfur conflict: The Humanitarian Ceasefire Agreement is signed by the Sudanese government and two rebel groups
- May 17 Massachusetts becomes the first U.S. state to legalize same-sex marriage
- May 26 The United States Army veteran Terry Nichols is found guilty of 161 state murder charges for helping carry out the Oklahoma City bombing.
- Jul 5 First Indonesian presidential election by the people - first round (eventually won by Susilo Bambang Yudhoyono)
- Nov 11 Yasser Arafat's death through unidentified causes confirmed by Palestine Liberation Organization, Mahmoud Abbas elected PLO chairman minutes later.
- Dec 8 The Cuzco Declaration is signed in Cuzco, Peru, establishing the South American Community of Nations.
- Dec 26 9.3 magnitude earthquake creates a tsunami causing devastation in Sri Lanka, India, Indonesia, Thailand, Malaysia, the Maldives and edges of the Indian Ocean, killing 230,000 people
- Sep 21 Green Day release their album "American Idiot" in the US
- Aug 27 German kayaker Birgit Fischer wins gold in K-4 500m & silver in K-2 500m in Athens; first woman in any sport to win gold medals at 6 different Olympics, gold 24 years apart, and 1st person to win 2 or more medals in 5 different Games
- Oct 27 The Boston Red Sox win the World Series for the first time in 86 years
Shrek the sheep from Tarras, Central Otago, New Zealand, is finally shorn live on TV after 6 years avoidance; the fleece weighed 27 kg (60 lb)
On April 28, 2004