Tradecraft

Tradecraft, within the intelligence community, refers to the techniques, methods and technologies used in modern espionage (spying) and generally, as part of the activity of intelligence. This includes general topics or techniques (dead drops, for example), or the specific techniques of a nation or organization (the particular form of encryption (encoding) used by the National Security Agency, for example).

In the books of such authors as thriller writer Grant Blackwood, espionage writer Tom Clancy, and spy novelists Ian Fleming and John le Carré, characters frequently engage in tradecraft, e.g., making or retrieving items from "dead drops", "dry cleaning", and wiring, using, or sweeping for intelligence gathering devices, such as cameras or microphones hidden in the subjects' quarters, vehicles, clothing, or accessories.

Jenkins, Peter, Surveillance Tradecraft, , Intel Publishing UK

...
Wikipedia