Intelligence is the gathering of information via covert means - eavesdropping, monitoring, spying, intimidation, bribery, etc. There are many forms of intelligence gathering which are referred to as disciplines. Some are:
Intelligence analysis is the process of taking known information about situations and entities of strategic, operational, or tactical importance, characterizing the known, and, with appropriate statements of probability, the future actions in those situations and by those entities. The descriptions are drawn from what may only be available in the form of deliberately deceptive information; the analyst must correlate the similarities among deceptions and extract a common truth. Although its practice is found in its purest form inside intelligence agencies, such as the Central Intelligence Agency (CIA) in the United States or the Secret Intelligence Service (SIS, MI6) in the UK, its methods are also applicable in fields such as business intelligence or competitive intelligence.
Frederick “Fritz” Joubert Duquesne (sometimes spelled Du Quesne; English pronunciation: /duːˈkeɪn/) (September 21, 1877 – May 24, 1956) was a South African Boer soldier, prisoner of war, big game hunter, journalist, war correspondent, Anglophobe, stockbroker, saboteur, spy, and adventurer whose hatred for the British caused him to volunteer to spy for Germany during both World Wars. As a Boer spy he was known as the "Black Panther", but he is also known as "the man who killed Kitchener", since he claimed to have sabotaged and sunk HMS Hampshire, on which Lord Kitchener was en route to Russia in 1916. As a German spy, he went by the code name DUNN. In 1942, he and 32 other members of the Duquesne Spy Ring were convicted in the largest espionage conviction in the history of the United States.