Spies usually come in two main types: those that gather intelligence themselves and those who recruit others to gather information for them.
The former are typically nurtured and watched over by a handler while working independently. The latter typically have worked under cover as diplomats, journalists and foreign businessmen.
Spies are associated most with international intelligence gathering. For example, procure missile and bomb designs and military codes for one country and given them to another as well as technology and data on radar, computers, machine tools and semiconductors. Another is to reveal spies of the other side. There are also industrial spies.
The best spies are often inconspicuous, scholarly types that are comfortable chatting up potential recruits at bars and parties and establishing friendships with them. Good spies also have skills in observation, analysis and surveillance.
Double agents are spies who work for both sides, usually pretending to be a spy for one side but actually working for another side. Moles are double agents whose identity is exceedingly secret and with access and a position as deep, hence the analogy.
Real spies are nothing like Ian Fleming’s James Bond. Bond spent his time seducing and assassinating while real spies spend their time recruiting moles and gathering intelligence information. Real spies rarely pick up a gun, let alone kill other spies in the field.
James Bond would be a highly inefficient spy. All he’s good at is running around, leaping into cars and shooting from cars. He’s more like a superior cop… but he would be a hopeless intelligence agent.
Spies need higher education, be skilled at writing, be well-read and boring – a nobody while being everybody.