The Secret Science of Dead Drops
Spies never actually meet to exchange secrets. Instead, they use a dead drop, which is a hidden location where items are left and retrieved at different times to ensure they remain anonymous.
By using a secret drop spot, agents avoid the risk of being spotted together in public. One person hides the materials, then leaves the area entirely before the recipient ever arrives. This physical separation prevents a chain of evidence from ever linking the two individuals. It is a simple but incredibly effective way to keep sensitive intelligence moving without anyone ever crossing paths.
Source: Dead drop