Updated 13 September 2002, 15.37
At first it seemed like a terrible accident. A plane crashed into one of the towers of the World Trade Centre.
But when a second plane hit the other tower the world woke up to a new kind of terrorism.
Now, 12 months on, we'd like to know how YOU feel the world has changed.
Maybe you have been directly affected by events, or you've become more aware of what's happening in the world.
Has any good come out of the tragedy of 11 September?
Unfortunately this topic is now closed but there are Comments pages on other subjects on the main Chat index.
Don┐t Forget 9/11
To shed a tear,
For those who died,
Who were full of fear.
And don┐t forget,
The heroic deed,
The fire fighters did,
They┐re the ones we need.
For those who helped,
And those who cared.
For those that were stuck,
And those that were scared.
So don┐t forget,
To shed a tear,
For those who died,
Who were full of fear.
Remember the love,
We had before.
Remember your friends,
And give them more.
Sophie, 13, Prestwood
At that time I was in school and the principal annouced that some children were going to be picked up, and I was asking myself why? Five people left before me and then my mom picked me up. She told me about the twin towers. I think I will never forget this. (I'm almost crying!!)
Yerilyn, 12, New York, USA
I didn't realize what had happened, but now whenever someone says 11 September, I remember. It makes me cry, and feel awful. I watched a show on it and there were some mobile phone messages victims left. It was dreadful.
Zara, 12, Andover
There are very few positive things that 11 September has achieved, the most significant is alerting the world that terrorism cannot be tolerated.
Andrew, 13, London
When I saw the plane hitting the World Trade Center, I just couldn't believe it. It was a terrible thing to watch on TV. I will never forget what happened, no one will.
Catherine, 14, Glasgow
11 September was a terrible day, with all the bad things that happened. It was an awful thing to happen, but it wouldn't have happened if all the people in the world could just live together in peace instead of going to war all the time, why can't they like each other? My best friend lives in South Carolina, USA near an air base for the US Air Force. She said it was really quiet after the attack because there was no longer any planes flying overhead. She sent me an email to tell me that she was OK. I was so glad!
Nikki, 11, Cheshire
I would just like to say a massive thank you to all the people on here for their support over the past year and how much everyone has helped everyone else, it really means so much to us all.
Amy, 15, New York, USA
11 September has changed the lives of so many people all over the world. The US appear to have woken up to the fact that they are not totally invincible. It is a shame that it took such a tragic disaster to make them see that the people in Afghanistan are suffering because they are now faced with yet another war to worry about.
Lisa, 14, Wymondham
I don't think there're any words we can say to help the families and friends of the victims. I just hope that there aren't any attacks tomorrow.
Helen, 14, Evian
Watching the footage of the 11 September tragedy was like watching a movie but with feelings. Since then the world has totally changed. I have written a poem about this and it carries a message in it:
"Bangs of guns,
screams of fright.
All this goes on day and night.
to the ones you love,
you want to give up,
when the going gets tough.
Skies are grey,
full of ash,
but hopefully this won't last.
When purity breaks through,
and people are equals,
when people can sit and talk without quarrels,
when skies turn from grey to crystal blue.
I may not live to see the day,
but I pray for those left behind.
Maybe one day,
the world's leaders will realise,
that war doesn't solve anything,
if they find this then,
blue skies will soon be heading our way".
Christina, 15, Amesbury
I was in school when it happened. At first our teacher wouldn't tell us what happened. Later on when we went to our homeroom class, our teacher told us what had happened for a while everyone just stared at each other then everyone started to talk. I was lucky because I knew about seven people who worked in Manhattan, but they all came home (late but they were safe). There was this boy in the other class, his mom had died but he tried to keep it a secret but soon everyone had found out. I think 11 September should be a holiday to remember what happened on that day and to remember the people that died.
Kayla, 16, New York City, USA
11 September was already a special day for me - my birthday. Last year, watching the terrible news of the terrorist attacks unfold, I realised how insignificant my presents and cake were in comparison to the terrible loss of life that had occurred in New York. I have since learned to give greater consideration to world problems and the impending war and not worry so much about my own minor concerns.
Harriet, 16, Havering
11 September was a tragic day for the whole world. I still remember it a whole year on. I feel sorry for the New Yorkers on this anniversary.
Rachel, 13, Prudhoe
11 September was horrible. Why did it happen? Just look at all the lives that where taken from us, don't the Taliban think of the innocent people they killed?
Heather, 15, Billingham
I remember 11 September so well. I can tell you what I was thinking and what I did on that day almost minute by minute. I was in school when it happened in my second period. I couldn't believe it. My best friend saw the Pentagon and was so afraid that someone she knew was hurt. Thankfully for her he wasn't, but that's not something many people can say. It changed the world that day and everyone in it. I remember watching the news and seeing so many people around the world going up to the American Embassies and it showed me how many people were thinking of it. I also remember seeing on the news our national anthem being played in front of Buckingham Palace and seeing all the people. It made me feel like Americans were not alone. I would like to say thank you to everyone who has supported America during this terrible event.
Karl, 15, Cold Spring, USA
I was searching for webcams online when the news broke. It just so happened that I clicked on the World Trade Centre webcam and it came up "Page not available". It wasn't until I got home that I saw what had happened. I have sent e-cards to all my American friends online saying that we are still thinking of them.
Harry, 15, Ceredigion
11 September is a tragic, tragic day, I was absolutely horrified when I learnt what had happened. My heart goes out to everyone who lost someone because of it. But it has also made me think how bad things are in third world countries for that sort of hate and discord to grow among people. And I appreciate the quality of life I am so fortunate to have.
Jenah, 14, New Zealand
11 September quite possibly changed the world forever. Not only did it kill thousands of people who worked in the World Trade Centre and the Pentagon. What about the passengers of the four airliners that were all killed and the effect it has on their families. I think they should build a monument at Ground Zero and mark the moment with the two minutes silence.
Craig, 16, Chicester
It made me sad that such a horrific thing could happen but proud of the way everybody rallied round and reacted, especially the courageous and tireless efforts of the New York fire department and the NYPD.
Helen, 14, Liverpool
It really made me realise how bad life is for some people and it's made me pay more attention to what's going on in the world. It was really, really terrible!
Susan, 13, Swindon
I think that 11 September was a truly terrible event, but some good has come out of it. I think that it has made everyone more aware of what is going on in the world. People are making the most of their lives now because they don't know if anything like this will happen again. I hope it doesn't.!
Sophie, 15, Pirton
11 September was a terrible day. I was at school and I remember watching the towers fall on live TV. My cousin was on the highway in front of the Pentagon when the plane crashed into it and my uncle works at the Pentagon. I felt like as if my world came to a crashing end. Luckily none of my relatives were injured. I wish many others could say that. My thoughts and prayers go out to the relatives of victims as we come upon the one year anniversary. God bless everyone!
Nell, 15, Maryland, USA
Although 11 September was a terrible tragedy and all those people died when they shouldn't have, it brought out something in everyone that no one thought they had. It made everyone realize that terrorism wasn't something that you give to someone else to deal with it.
Sarah, 13, Lerwick
I think it was probably the most tragic event in history and it is so sad that so many thousands of people have lost friends and relatives. It affects everyone because people are still so shocked and upset.
Tessa, 12, Leicester
11 September was a horrible event that should never of happened. It's hard to believe how many people it's affected. My good neighbour had a dad who was in there and died. The tragedy has brought people closer together, and we've realized who our real friends are. I was in school at the time of the tragedy and we started watching the news. All of our other problems were forgotten. My teacher said that it would be something to tell your grandchildren that you were there, and you saw it happen.
Brittany, 11, South Carolina, USA
I live in Brooklyn close to the bridge that gets you into Manhattan. We were horrified when we saw it happen, some of us started to cry because some of our family worked in the WTC or in Manhattan. Our parents had to walk home and they picked us up from school. I looked up to where the towers were suppose to be and they weren't there. When I got home only one channel worked and it was a Spanish channel. It was weird because all the stores were closed and everything was shut down, it was like a ghost town. All the hospitals were full and sometimes all you could hear were sirens and helicopters. September 11, 2001 is a day I will always remember, always.
Vikki, 13, Brooklyn, USA
It makes me feel glad for the tightened airport security. I never want anything like it to happen again. It was terrible.
Amanda, 13, Thamesmead
It's made me watch the news more and aware of what's happening in the world.
Frankie, 13, London
September 11th is a day I will never forget. I remember what happened on that day, my mom picked me up from school and she said there was something going on in America. She took me home and I sat in front of the television watching the news until 7pm. It's such a sad day in the world's history.
Luke, 14, Birmingham
I think it's made more people aware of what's happening in the world and also of how lucky we are compared to other people in the world. It was still an awful thing though, which should never have happened.
It made me think about just how much we all need to back each other up in today's world and look out for each other. Britain has been beyond nice to us, I think it's time we did something to show them how much appreciated their support is.
Kaleigh, 12, Wethersfield, USA
It's made me think about how tough it must be growing up in Afghanistan.
Ryan, 12, Totnes