As our nation and the world reflects on this day, millions are mourning the lives lost 13 years ago in the terrorist attacks on September 11, 2001. While everyone grieves, remembers and reflects in their own way, social media has been a common place for the world to gather and share their thoughts in a collective, united way, with the hashtags #NeverForgetSeptember11 and #Remember911 trending all day.

Our thoughts are with the thousands who lost their lives on this day 13 years ago, and anyone who was affected by this tragedy.

Here are how some celebrities have chosen to express their remembrance of 9/11: