It has no formal structure, no clear leaders and no official spokesperson. Yet the "Indignados" movement remains a potent force in Spain, where protests against the handling of the economic crisis continue.
In mid-2011, the Socialist government of Jose Luis Rodriguez Zapatero began sinking billions of euros into Spain's failing banks and imposing spending cuts, the likes of which had not been experienced for at least a generation.
Tens of thousands of people reacted by camping out and rallying for weeks in town squares in spontaneous protest against the country's economic and political system. That helped spark the global "Occupy" movement.
Ivan Ayala, a 31-year-old university researcher in macroeconomics, joined the Indignados (Indignants) movement, as it became known, soon after protests began.
Frustrated with Spain's political parties, he started going every day after work to Madrid's main square, Puerta del Sol, to participate in the movement.
A year on, the Socialists have been voted out, but unemployment is still around 25 percent and the country has accepted a 100 billion-euro bailout for its banks. Ayala continues to meet at least twice a week in a public square to debate economic policy with the group, also called 15-M after its May 15 beginning, which continues to organize regular demonstrations against banks and the government.
While 15-M is not a political organization, Ayala sees it as a social force holding politicians to account, affecting public policy and giving a voice to hard-up taxpayers and the unemployed. He likens it to social movements of the past, such as that demanding votes for women a century ago.
The group has achieved some concrete change. After months of 15-M protests against evictions of poor families who had defaulted on their mortgages, the government cajoled banks into signing up to an ethical code intended to delay evictions by two years in cases of families with no income.
Ayala, who runs his own business in Madrid exporting ethical products such as food and make-up, is skeptical that the euro zone's promised bailout of Spanish banks will stem the crisis. Like many critics of the euro project, he believes its foundations are flawed because of the diverse nature of the economies it has sewn together.
"Independently of the financial crisis, the euro crisis would have happened - it has just brought it forward," he said. "The solution would have been to not have gone into the euro."
He likened Spain's membership of the single currency to "sleeping with a gorilla".
"The gorilla is Germany, which has a different income, a different economic structure, very strong industry. Spain enters in this context and loses all its economic tools like the exchange rate."
Without giving the ECB the power to buy sovereign debt on the primary market, austerity measures in the region will fail to stem the crisis and could lead to the breakup of the euro zone, Ayala said. He views the prospects for Spain as grim.
"As Europe is at the moment, the euro is impossible to maintain because Spain is condemned to two, three lost decades, as Latin America was. I think they are going to throw Spain out of the euro and in the end it will be a relief."
Without the ability to let its currency devalue, there is a risk Spain will have to force salaries down to levels intolerable for a country where one in four is already jobless.
Ayala and other Indignados are not prepared to let that happen.
Most recently, 15-M raised money to file a legal case against Spain's fourth largest bank Bankia, being bailed out by 23.5 billion euros of public money. The case names former Bankia chief Rodrigo Rato, who is also a former Spanish economy minister and former managing director of the IMF.
"We need to go to politicians' homes, to shout, to bang pots and pans in front of all those politicians we suspect of having followed or following austerity policies that remove doctors or education," Ayala said.
(Reporting by Erik Kirschbaum, Noah Barkin and Annika Breidthardt in Berlin, Luke Baker in Brussels, Sarah Morris in Madrid, Eva Kuehnen, Andreas Framke and Paul Carrel in Frankfurt and Steve Slater in London.; Editing by Sophie Walker and Richard Woods)