It's official. We'll be heading to the polls for the federal election on May 21. Up until the announcement on Sunday, we were all speculating on when it would be, with the most likely dates falling on May 21 or May 14. How did we all seem to know that the election would be in late May? Federal elections must be held every three years. That means, the election had to be called by 21 May, which was the third anniversary of the first meeting of the outgoing parliament. If the Prime Minister didn't call an election before the three years ended, the House of Representatives would still be dissolved by May 21. So, every three years, Australia votes for a new House of Representatives. Also known as the lower house, this is where your local members end up once they've been elected. It also votes for half of a new Senate because half of those sitting senators have come up for re-election, while the other half remain in their seats. So in order to call an election, the Prime Minister will visit Government House in Canberra to ask the Governor-General to dissolve the parliament and issue 'the writs'. This is the formal instruction to the AEC to hold an election. There needs to be between 33 and 68 days between the issued writs and the day of the election. If you have not enrolled to vote yet, you will have until 8pm on the seventh day from the writ being issued to enrol. So that's seven days after the election has been called. This is because the AEC needs time to process the new enrolments. Those who are looking to be nominated for a seat in parliament will have between 10 and 27 days from the writs to put themself forward. Once the nominations have closed at midday, they have to be declared within 24 hours. The AEC will then carry out a draw to determine where each candidate will appear on the ballot paper. The candidate that takes the enviable top position is said to have picked up the 'donkey votes'. What is a donkey vote? It's when a voter numbers the candidates in the order they appear on the paper. It will still be counted because they have technically followed the voting instructions. A donkey vote is not an informal vote, which is a vote that does not count because it has not followed the voting instructions. For example, if the voter draws a flower (or something more explicit...) over the ballot paper, instead of numbering the candidates. This kind of vote will be discarded and won't count towards the allocation of seats in parliament. It is, essentially, a wasted vote. Avoid making an informal or a donkey vote on election day, and arm yourself with an informed understanding of who's running for your electorate.