A ten part series narrated by Oliver Stone, covering the history of the United States of America since World War II up until sometime after Osama bin...
Since it's an educational group, we'll start with a definition:
1. lack of integrity or honesty (especially susceptibility to bribery); use of a position of trust for dishonest gain
2. in a state of progressive putrefaction
3. decay of matter (as by rot or oxidation)
4. moral perversion; impairment of virtue and moral principles; "the luxury and corruption among the upper classes"; "moral degeneracy followed intellectual degeneration"; "its brothels, its opium parlors, its depravity"; "Rome had fallen into moral putrefaction"
5. destroying someone's (or some group's) honesty or loyalty; undermining moral integrity; "corruption of a minor"; "the big city's subversion of rural innocence"
6. inducement (as of a public official) by improper means (as bribery) to violate duty (as by commiting a felony); "he was held on charges of corruption and racketeering"
1. An agreement to perform together an illegal, wrongful, or subversive act.
2. A group of conspirators.
3. Law An agreement between two or more persons to commit a crime or accomplish a legal purpose through illegal action.
4. A joining or acting together, as if by sinister design: a conspiracy of wind and tide that devastated coastal areas.
The third definition means that the intention is of zero capability to justify any used means.
1. a secret plan or agreement to carry out an illegal or harmful act, esp with political motivation; plot
2. the act of making such plans in secret
Corruption, a noun that can be created from the adjective 'corrupt':
1. Marked by immorality and perversion; depraved.
2. Venal; dishonest: a corrupt mayor.
3. Containing errors or alterations, as a text: a corrupt translation.
4. Archaic Tainted; putrid.
A conspiracy is often established, its secrecy, to avoid any prosecution. If you can cover up your crimes, you'll avoid to be prosecuted. It is that simple. And a cover-up can be many different things: a destruction of evidence, a lack of transparency, dishonesty, partially untrue statements (making entire statements invalid), strictly selective choice of sources or their parts, classification, etc.
Also, there are some hidden ordinary groups (causing completely zero harm to anyone), or groups, which avoid dragging attention to them to avoid any unjust persecution. An example of such a group can be a neo-pagan group, which hides its rituals and gatherings to avoid any religious intolerance. Members of such groups can also hide their true religious beliefs, claiming being a member of one of the major religions. Such persecution is rare nowadays though, due to more scrupulous laws being introduced.
Iraq for Sale, a film regarding companies making profit at the cost of safety and quality:
Historic conspiracies, examples: Second Catilinian Conspiracy, Assassination of Julius Caesar, Assassination of Caligula, Pisonian conspiracy, Pazzi Conspiracy