Half a million people from across the public sector came out on the streets or joined picket lines in England and Wales demanding better pay and conditions in what has been described as the biggest coordinated industrial action in decades.
Among those on the streets are some 300,000 teachers on day one of a nationwide strike affecting more than 23,000 schools.
Recently released figures show that 5 in 10 of those who had qualified as teachers over the past 10 years have since left the profession because they felt undervalued and underpaid.
The participating teachers say they don't want to be on strike today and that all they're asking for is more funding for their schools and higher wages for themselves.
Darren has been a teacher for more than a decade.
In 2010 we went into austerity, our pay was frozen, and we've come out of austerity, about to go back into it again. And we're losing out in terms of real terms pay. It's not just about the cost of living crisis. This has been going on for years, and we've had enough.
Darren, Striking Teacher
The government has called the walkout unfair to the parents and children with the education secretary, Gillian Keegan, saying inflationary rises will make things worse, and that these are unprecedented economic times.
The teachers, however, blame government inaction which is ultimately hurting students.
... its a knock on effect, so they are not funding the increases in pay that they promised to teachers, so the money is coming out of the school's existing budget. Not being able to get extra (funds) to pay extra to the teachers. So that means class places are increasing, it means that we cannot take children on trips.
The demand for inflation busting pay rises is shared by the hundreds of thousands of others in the public sector, such as the health service, as well as University staff, civil servants and train drivers, who are also striking today.
More walkouts are planned for the coming weeks, meaning the UK's winter of industrial discontent continues to grow.