The Iran-Contra Scandal was a political scandal that occurred in the last two years or so of Ronald Reagan’s presidency. It had to do with the administration secretly selling weapons to Iran and using the profits from those sales to help fund the “Contra” rebels in Nicaragua.
The weapons were sold to Iran for two main reasons. First, the US hoped that it could make friends among what it thought were moderate Iranians who might make that country more pro-US after its radical leader, the Ayatollah Khomeini, died. Second, the US hoped that the Iranians would put pressure on terrorist groups that they supported in Lebanon. These groups were holding American hostages and the US hoped they would free those hostages.
The administration then took the money from the arms sales and funded the Contras. These were rebels fighting the Nicaraguan government, which was strongly influenced by Marxism. The Reagan administration wanted to fund the Contras as a way of containing communism. However, such funding was illegal according to a law passed by Congress.
The scandal centered largely on how much President Reagan and other top officials knew about the arms sale and the funding of the Contras.