Add Yahoo as a preferred source to see more of our stories on Google. Need some gifts for your kids, grandkids, nieces and nephews? More specifically, gifts they won't toss aside as soon as they open ...

Prisoners, Lovers, & Spies is the first history of invisible ink and secret communications revealed through thrilling stories about scoundrels and heroes and their ingenious methods for concealing ...

The Secret Intelligence Service (MI6) experimented with semen as a form of invisible ink, a recently-published diary entry has revealed. Walter Kirke, deputy head of military intelligence at GHQ ...

Do you like real life spy secrets, declassified documents and Ian Fleming novels? Then you might be tempted to bookmark this page at the CIA's Electronic Reading Room. In a fairly recent bow to ...