The close of nominations on Wednesday signalled the official beginning of the Presidential Election campaign.
Three people have been successful in their bid to contest the race for Áras an Uachtaráin: Catherine Connolly, Jim Gavin and Heather Humphreys.
The last time there were only three candidates was the 1990 contest, when Mary Robinson, Brian Lenihan and Austin Currie battled it out.
Ms Robinson ultimately won, and became Ireland's first woman President.
Support
Ms Connolly is an Independent TD, who has received the backing from left-leaning political parties in the Oireachtas, including Sinn Féin, Labour, the Social Democrats, the Greens, People Before Profit and Solidarity.
Mr Gavin is the Fianna Fáil election candidate, while Heather Humphreys won the contest to become Fine Gael's candidate.
To win, the successful candidate needs to secure substantial support from beyond their base.
Campaign
There are 30 days in the presidential campaign.
Both Ms Connolly and Ms Humphreys have held their official campaign launches, and it is expected Mr Gavin will hold his event this weekend.
After that, the candidates will be campaigning constantly in every county. It's going to be a gruelling four weeks, in which the candidates are constantly on the stump or in radio studios explaining who they are and what's their vision for the presidency.
The Presidential Election is viewed as a particularly difficult contest because the limited role of the presidency often means that the media focus is on the individual rather than their campaign platform.
TV Debates
A key moment in the presidential campaign will be the television debates of which there will be two: one will be hosted by RTÉ's Prime Time and another by Virgin Media.
The Virgin Media TV debate will take place on Monday 29 September.
As well as the Prime Time debate, RTÉ will host several debates, including on The Week In Politics on Sunday 5 October.
Debates will be expected too in the last two weeks of the campaign. That is a time when the voting public really begins to make-up its mind on which candidate to back.
That is what makes them so crucial and, for the candidates, the strategy is often to play safe rather than go for broke.
Of course there will be a plethora of radio interviews.
Social media will be another key electoral battle ground.
Swings
The electorate can be quite volatile in Presidential Election campaigns.
In 2011, the Independent candidate Seán Gallagher appeared to be on the cusp of becoming Ireland's "first citizen" only for his support to slide following a controversial RTÉ TV debate.
In 2018, there was a surge in support for the Independent candidate Peter Casey following remarks he made about the Travelling community.
This explains why political parties will pay attention to opinion polls, but won't really believe what they see until the final two weeks.
Polling
Polling day is set for Friday 24 October. To be able to vote in a Presidential Election, you must be: an Irish citizen; aged 18 or over; registered to vote; and ordinarily resident in Ireland.
If you're unsure if you are registered to vote, it's possible to check your details on checktheregister.ie.
Result
The count will begin on the morning of Saturday 25 October and a result should be known by 9pm that night.
In the last Presidential Election in 2018, Michael D Higgins secured 822,566 first preference votes, or 55.8% of the ballots which had been cast, and was elected on the first count.
