Gold nanorods (AuNRs) have attracted high attention because of their multifunctions and potential applications in optical, electronic, catalytic and biomedical areas. This study demonstrates a key role of silver (Ag) atoms/clusters, experimentally and theoretically, in the formation and growth of AuNRs. It was found that the addition of silver salt (silver nitrate) can preferably deposit on certain Au crystalline {100} and/or {110} facets to affect the stacking of Au atoms when form and grow to AuNRs in the reported reaction system, resulting in slower atomic stacking on these two {100} and {1...