I have noted that many people, having completed a cemetery visit, leave a small stone / pebble atop the gravestone of the deceased. Is there a religious requirement to do so, or is it simply custom (though possibly for a specific purpose)? I have also noted that in other countries NO-ONE leaves a small stone / pebble atop a gravestone, and when I asked why this was NEVER done I was generally looked at incredulously. Is the practise Law or custom, and if custom, for what reason or reasons might this be done?

The source to this custom is in Baer Heitev 223; 8. The reason behind this custom is to show respect to the deceased and that we will not forget him. In addition, it is showing in a way we want to participate in contributing to the building of the Matzevah. There are those who hold that the custom in ancient from the times there was no gravestone, just a pile of stones on the grave place. (See Nishnah Shqalim 1, 1) This is a widely practiced custom by many communities but not by all…