Protesters heckled Hillary Clinton as she arrived to make her acceptance speech at Queen's University in Belfast.

The longest war in United States history, has come at a cost of over $2.2 trillion, with around three and a half thousand NATO troops killed and more importantly, over 50,000 Afghan civilians killed, a conservative estimate, has millions displaced or turned into refugees.

US and NATO troops began to withdraw from the war-torn country last week amid a sharp spike in Taliban attacks across the country.

The incumbent president appears to have gone on a federal killing spree, executing more prisoners since he's been in power than all other state executions combined, making him responsible for more executions than any other modern president.

The winner of US presidential elections is not always the candidate who wins the most votes nationally, as Hillary Clinton learned four years ago.

The United States uses a system known as the Electoral College system to elect a president once every four years; however, many people are in the dark as to what that means and how it works.