Relating to the world's Stock Markets - the activity of dealing in stocks and shares supported by confidential information not known to the market at large, for personal profit or gain. Illegal - everywhere.
You have some confidential information about a company quoted on the Stock Market - which is not known to other investors. You exploit this information by buying/selling shares before the rest of the market knows. You make lots of money - unfairly and illegally. You end up in prison - what else did you expect.