Short answers, pulled from the story.
The Iran-Contra affair was a political scandal involving senior Reagan administration officials who secretly sold arms to Iran between 1981 and 1986 and used the proceeds to fund the Nicaraguan Contra rebels, in violation of the Boland Amendment, which Congress had passed to prohibit such funding.
The stated justification was to secure the release of seven U.S. hostages held in Lebanon by Hezbollah, which had ties to Iran. Administration officials also believed they were building a relationship with a supposedly moderate Iranian faction associated with Akbar Hashemi Rafsanjani, the speaker of the Iranian parliament, to reestablish U.S.-Iranian ties after the expected death of Ayatollah Khomeini.
The Boland Amendment refers to three U.S. legislative amendments passed between 1982 and 1984 that prohibited U.S. government funding of Contra military operations in Nicaragua. The second Boland Amendment, in effect from the 3rd of October 1984 to the 3rd of December 1985, extended the ban to all U.S. intelligence agencies and entities. The Reagan administration secretly circumvented the ban by routing money from the Iran arms sales to the Contras through an off-the-books network called the Enterprise.
Oliver North was a military aide to the U.S. National Security Council. He proposed and ran the plan to sell arms directly to Iran at a markup and divert the proceeds to the Contras, working closely with National Security Adviser John Poindexter. North was indicted on 16 charges and convicted of accepting an illegal gratuity, obstruction of a congressional inquiry, and destruction of documents, though those convictions were later overturned on appeal.
President George H. W. Bush pardoned six figures on the 24th of December 1992, including Elliott Abrams, Duane Clarridge, Alan Fiers, Clair George, Robert McFarlane, and Caspar Weinberger, who had not yet stood trial. Independent Counsel Lawrence Walsh stated that the pardons completed a cover-up that had lasted more than six years.
Thomas G. Clines, a former CIA clandestine service officer, was the only Iran-Contra defendant to serve a prison sentence. He was convicted of concealing profits he earned helping run the Enterprise and failing to declare foreign financial accounts, and served 16 months in prison.