Hundreds of thousands of workers went on strike across the Republic of Ireland
It comes amid a pay dispute between public sector workers and the Irish government.
More than 300,000 workers are on strike across the Republic of Ireland, including nurses, doctors, teachers and civil servants.
It comes amid a pay dispute between public sector workers and the Irish government, with further strikes planned for October 21.
Schools are expected to be closed as hospital appointments are canceled and protest lines form across the country during the 24-hour strike.
By the end of September, more than 100,000 workers, including nurses, school workers and civil servants, had moved to take legal action.
In the beginning of October, the teachers of primary and secondary schools in the republic started to work.
Previously, approximately 97% of Forsa members voting in industrial ballots voted in favor of action. It is the largest public service union of the republic.
SIPTU branch organizer Brendan O'Brien, which represents public and health sector workers, previously said workers' "good will" was a big part of what kept the public service going.
However, he said the Irish government's failure to lay the groundwork for formal talks "has left our members with no option but collective action".
On Tuesday, Jack Chambers, the republic's spending secretary, described the strike as "deeply disappointing" and said it would cause significant disruption to the economy, with thousands of hospital appointments canceled and schools closed.
Dawn Hutchins-Walsh is a teacher at Hartstone Community School in Dublin and commutes from County Wicklow every day.
"Salaries don't last as long as they used to," he told Irish broadcaster RTÉ.
His colleague Sinead McCarthy said he had to go to Dubai for a few years to save money for a deposit.
"It's not possible to save for a house in Ireland with the conditions and the money we have here in this country," he said.
Linda Kelly, general secretary of the Association of Secondary Teachers of Ireland (ASTI), said teachers were "really struggling with their pay".
"They don't feel the government is taking them seriously, there's a lot of frustration with the government's approach to liberalization over the last few months.
"There's been enough time to sort this out and the government is sitting on its hands and this is the result now," Kelly told RTÉ.