The annual tradition of wearing poppies started as a way to remember the glorious dead of World War I, also known as the Great War. Since then it has evolved to include all of the uniformed men — and women — who made the ultimate sacrifice for their country.
This visible symbol of remembrance culminates with a two-minute moment of silence at 11 o'clock in the morning on the eleventh day of the eleventh month, best known as Remembrance Day, Armistice Day or Veterans Day. (In the British Isles, major public ceremonies are held on Remembrance Sunday, which is the Sunday closest to November 11. This year, that's November 9.)
Poppies are available just about everywhere in Britain as well as in Canada, including at many Tim Hortons cafes. The Royal British Legion also has distributors in many major U.S. cities.