hold on means wear a short time (e.g. Please hold on while I transfer you to the Sales Department.)
hold onto means hold firmly as long as possible (e.g. Hold onto your money so you can buy some duty free gifts on the way back.)
hold on means wear a short time (e.g. Please hold on while I transfer you to the Sales Department.)
hold onto means hold firmly as long as possible (e.g. Hold onto your money so you can buy some duty free gifts on the way back.)