Sitting in History class. That's where I was on September 11, 2001 when we heard the news. I think that's how it is for everyone - you remember and will always remember exactly where you were that day, that moment.
September 11th was a day that will never be forgotten. It was a day of tragedy, of loss, of sadness. Now 10 years later, people around the US (and even around the world) are remembering that day and coming together.
So today we remember those that were lost 10 years ago. And we also use today to be reminded of the important things in life.