Today is the 18th anniversary of the September 11th attacks.
Almost 3,000 people died on September the 11th 2001 in the worst act of terrorism on American soil.
Today - 18 years later - they will be remembered at a commemoration at Ground Zero in New York,
As has happened in years past, the names of those killed at the World Trade Center, Pentagon and aboard Flight 93 will be read during the ceremony.
This evening, a public ceremony featuring the public art installation Tribute in Light will open to the public as the sun sets.
Social media users commemorating the anniversary are being encouraged to use the hashtag #Honor911.