19 January 2012 Last updated at 16:32

The US elections and mid-terms

Although US elections happen thousands of miles from the UK they are often big news here too.

That's because decisions made by the US government often affect people all around the world - things like whether to go to war, and how to protect the environment.

Presidential elections

Every four years people in the US vote to elect their president, and the four years between elections is called a term of office.

Politicians can only serve two terms of office, and if they win two elections they are not allowed to stand again in a third one.

Mid-terms

There are other elections halfway through each term of office called mid-terms.

They select lots of US politicians who work in two government buildings or houses called the House of Representatives and the Senate.

Together the buildings are called Congress.

Both US political parties - Republicans and Democrats - want to control the houses by having more politicians elected to them than their opponents.

If the houses are controlled by the party different to the one of the president it can be very hard for him to do what he wants.

Donkeys and Elephants?

The Republican and Democrat parties are often symbolised by animals - the Democrats are represented by a donkey and the Republican party symbol is an elephant.