When a boy reaches 12 years old, his nedarim (vows) are considered to be binding. However, I don't believe I've ever seen a 12 year old boy make Hataras Nedarim on Erev Rosh HaShanah. Is there a reason why they don't, or is it done and I have just not seen it?
(Please feel free to edit this question or add comments to expand on the sources that I have purposely left out because of a lack of knowledge.)