Data seepage refers to small pieces of information leaked from computers and networks that may not seem important individually but can reveal greater details when combined. This occurs through network protocols like WiFi, DHCP, and DNS queries that broadcast system details. By monitoring these protocols, one can determine locations visited, social connections, internal workstation names, and more about a person that could aid in social engineering or targeting network attacks. The best protection is awareness of what information leaks from systems and avoiding working on untrusted networks.