Irish citizens are eligible to vote in six different types of election.

General elections see the country decide on which TDs will represent them in the lower house of the Oireachtas called Dáil Éireann; once elected, these TDs will form the Government and pass laws. General elections must be held every five years at most in Ireland (though they are held more often than that if the Government of the day falls or if an early election is called).

Bye-elections are held when a sitting TD retires, resigns or dies between general elections. The system is the same as for general elections, except only those in the TD’s original constituency are allowed to vote - unlike other elections, they are not a national event and only one seat is filled. Bye-elections must be held within six months of the TD leaving the Dáil.

Seanad elections are held a few weeks after general elections and see the election of senators to the upper house of the Oireachtas. They are slightly more complicated because not everyone is allowed to vote in them.

Of the Seanad’s 60 members, only 49 are elected - the other 11 are nominated by the new Taoiseach. And of those 49 elected senators, just 6 are officially elected by university graduates of National University of Ireland universities (UCD, Maynooth, Galway and UCC) and Trinity College; those who aren’t graduates of these universities aren’t given a chance to vote. The remaining 43 senators are selected by members of the incoming Dáil, members of the outgoing Seanad, and members of city and county councils.

Presidential elections allow the country to decide on who becomes president, and take place within the 60 days before the sitting President's term expires. Presidential terms last for seven years and a sitting President can run again, but only once.

Local elections which allow people to vote for city and county councillors on local authorities. These elections are also held every five years.

Councillors create policies for local authorities, which are in charge of services such as roads, planning, housing, parks, community development, environment, and things like libraries and fire services.

European elections are also held every five years, usually at the same time as local elections. These see Members of the European Parliament (MEPs) decided upon, where representatives are voted to become politicians in the main law-making body of the European Union.

The parliament elects the President of the European Commission, the EU’s main executive body which manages EU policy, and appoints Commissioners, as well as setting the EU’s budget. 

The European Parliament is in many ways the EU’s counterpart to the Dáil, whereas the Commission could be compared to a national government involving different ministers. 

Aside from elections, citizens can also cast their votes in referendums.

There are two types of referendum: a Constitutional referendum, which decides whether changes can be made to the Irish Constitution, and an ordinary referendum, in which a ballot would be held if the President of the day decided that a proposed law was of enough national importance to warrant a vote by the people.

In order to vote, citizens must by both eligible and registered to do so.

Regardless of the election, eligible voters must be over 18 years old and reside in Ireland. Crucially, they must also be on the electoral register, which is a database of voters and where they live (which is important information that decides the constituency that a person can vote in).

There are different allowances for different nationalities.

Irish citizens can vote in every election - with the exception of Seanad elections, where people must be a graduate of Trinity College or an NUI university, or an incoming TD, an outgoing Senator, or a member of a local authority.

British citizens who live in Ireland can vote in general elections and local elections, as well as relevant byelections.

EU citizens resident in Ireland can vote in local elections and European elections; for the latter, they must complete a declaration to prevent double voting in their home country.

Non-EU citizens are allowed to vote in local elections only.

On voting day, polls are usually open from 7am until 10pm.

In Ireland, all elections – Dáil, Seanad, presidential, European and local elections – are decided by secret ballot through a system called proportional representation with a single transferable vote (PR-STV).

Voters indicate their first and subsequent choices for the candidates on the ballot paper by marking the relevant number in the box beside a person’s name. They indicate their first choice by writing ’1′ opposite that candidate and ’2′ opposite your second choice, and so on.

By doing so, they are instructing that their vote be transferred to a second preference if their first choice is either elected with a surplus of votes over the quota or is eliminated.

If a person’s second choice is elected or eliminated, their vote may be transferred to their third choice, and so on. People can order some or all candidates or stop at just one.

During referendums, the choice is instead a binary one with two boxes: one indicating Yes and another indicating No. The voter simply marks an X in the box of their choice.

In most cases, people will vote at their local polling station. This will be indicated on their ballot, which will be posted to them at their home address a couple of weeks before the day of the election or referendum.

There are a few small but important rules around casting a vote in any of the above scenarios. The main one is that marks can only be placed inside the relevant boxes - numbers if it’s an election or an X if it’s a referendum; anything outside the box or anything else that’s written on the ballot will result in a vote being discounted, known as a spoiled vote.

After the ballot is marked, the voter folds the ballot and places it in a large metal box outside the polling booth. These boxes are then collected and transferred to the local area’s count centre, where the individual votes are counted and feed into the final result.

Citizens can also apply to vote via post. In this scenario, the voter is sent documents before polling day and returns their ballot paper by post.

In Ireland, counting begins on the morning the day after a vote is held.

In the case of a referendum, the process is more straightforward: votes for and against the referendum proposal are counted in each count centre, where counting may be watched by members of the Oireachtas or other approved bodies.

Local returning officers report the result to the referendum returning officer, who collates results from all constituencies. Once those results are counted, the referendum returning officer draws up a provisional referendum certificate which states the overall result of the voting.

A referendum is approved if more than 50% of the votes are Yes (and it is rejected if more than 50% of the votes are No). Afterwards, the provisional certificate is published and if this states that the result was a Yes to amend the Constitution, a new bill is signed into law and the Constitution is amended.

Things are slightly more complicated in elections, because candidates can be eliminated and votes are transferred depending on a voter’s order of preference.

On the morning of the vote at the count centre, all the ballot papers are mixed and then sorted according to first preferences.

Spoiled papers those without an official stamp; those which do not indicate a clear choice, or those with any text or anything written on the ballot paper outside the boxes – are removed.

The quota, the minimum number of valid votes each candidate must get to be elected, is then calculated.

The quota is calculated based on the number of votes cast and the number of available seats in a given constituency.

In a three-seat constituency, for example, the quota is a quarter of the valid votes, plus one – only three candidates can get this number of votes. In a four-seater, the quota is a fifth of the valid votes, plus one, and so on.

Candidates are elected once they reach the quote and if a candidate receives more than the quota on any count, their surplus votes are transferred to the remaining candidates in proportion to the next available preferences indicated by voters.

The Citizens' Information site has given this breakdown as an example:

If a candidate receives 900 votes more than the quota on the first count and, on examining their votes, it is found that 30% of these have next available preferences for candidate B, then candidate B does not get 30% of all candidate A’s votes, candidate B gets 30% of A’s surplus, that is, 270 votes (30% of 900).

Where a candidate is elected at the second count or a later one, only the votes that brought them over the quota are examined in the surplus distribution – i.e. the votes last transferred to the elected candidate.

The manner in which the surplus is distributed depends on whether the number of transferable papers is greater than, less than or equal to the surplus.

If two or more candidates exceed the quota at the same time, the larger surplus is distributed first. The surplus must be distributed if it can elect a candidate or save the lowest candidate from elimination or qualify a candidate to recoup their election expenses or deposit.

The last seat can be filled either by a candidate exceeding the quota or being elected without reaching the quota because it is clear that they are ultimately going to be elected.

Candidates can ask for a recount of a particular count or of the entire count.