Maltego is an Open Source Intelligence (OSINT) tool, not to be confused with an open source project.  Open source intelligence is form of intelligence collection management that involves finding, selecting, and acquiring information from publicly available sources and analyzing it to produce actionable intelligence. In the intelligence community (IC), the term "open" refers to overt, publicly available sources (as opposed to covert or classified sources); it is not related to open-source software or public intelligence.