For many kids growing up, being a spy was the ultimate cool job. James Bond, Jason Bourne, Jack Ryan and Ethan Hunt are some of the most popular fictional spies in the world.
But espionage isn't just for film – it's an important and highly secretive profession.
Instead of introducing themselves as Bond, James Bond, a spy will likely have multiple aliases, and be a tad more discreet than Ian Fleming 's protagonist.
