What do coins on military tombstones mean?

Have you ever been in a cemetery and saw coins laying on a tombstone?

Col. Dave Taylor, a Vietnam War veteran, explained the tradition and the reason behind it.

A coin left on a headstone lets the deceased soldier's family know that somebody stopped by to pay their respects.

If you leave a penny, it means you visited. A nickel means that you and the deceased soldier trained at boot camp together. If you served with the soldier, you leave a dime. A quarter is very significant because it means that you were there when that soldier was killed.

Taylor says the tradition became popular in the United States during the Vietnam War. It is believed it was a way to show respect without getting into an uncomfortable political discussion about a war that was very controversial.