text: The Catalan regional parliament has voted to start the secession process, but Prime Minister Mariano Rajoy has gone to the Constitutional Court to suspend the resolution.
  Secession is banned under Spain's constitution and the prime minister has accused campaigners of trying to "liquidate" the nation.
  When Catalan nationalists held an unofficial poll in November 2014, 80% of those who voted backed independence.
  The vote was non-binding as the Constitutional Court had ruled it illegal. But the secessionists viewed it as a defining moment and declared regional elections in September 2015 would be a de facto referendum on independence.
  Catalan nationalist parties won an absolute majority in the 135-seat regional assembly and on 9 November pushed through a motion to start the process towards independence.
  The Spanish government has hit back, declaring the secessionist step unconstitutional.
  The votes suggest they have popular support, but last November's non-binding poll was based on relatively low turnout of 2.2 million voters out of a potential 5.4 million.
  And the Junts pel Si (Together for Yes) coalition of two major separatist parties which won this year's regional election relied on the support of a radical left-wing party, CUP, to secure its majority in the Catalan parliament. Even then, they fell short of a majority of voters, with 48% support.
  So the secessionists control the regional parliament but Catalan opinion on secession appears evenly divided.
  And with Spain facing a general election on 20 December, and no party expected to win a clear majority nationally, the Catalan issue is only adding to political uncertainty.
  Catalonia - its history, politics and language
  That is the process that the Catalan parliament has voted to start - with plans for legislation to begin by early December on a separate constitution, treasury and social security system.
  Catalans already have extensive autonomy in education, health and policing. But acting Catalan President Artur Mas wants the rapid creation of other trappings of an independent state, too, such as a diplomatic service, central bank and armed forces.
  But Spain's Prime Minister Mariano Rajoy, whose Popular Party is facing a critical test in December national elections, may invoke article 155 of the constitution that allows the national government to compel an autonomous regional authority to meet its constitutional obligations.
  Before the 2014 vote, he took the case to the Constitutional Court and the poll was declared illegal. Artur Mas is facing criminal charges as a result. And now Mr Rajoy has returned to the court to have the regional assembly's motion suspended.
  But there is a growing demand in Madrid for the government to engage with Catalan leaders.
  So far, the independence movement remains peaceful and organised, in stark contrast, for instance, to the separatist violence which plagued the Spanish Basque Country until recently.
  Spain's rapid return to democracy after the death of dictator General Francisco Franco in 1975 brought devolution for Catalonia, along with Spain's other regions.
  Prosperity followed, with Barcelona becoming one of the EU's most high-profile cities, famed for its 1992 Summer Olympics, trade fairs and its football.
  But Spain's economic crisis hit Catalonia hard, leaving it with 19% unemployment (compared with 21% nationally). The region, which makes up 16% of Spain's population, accounts for almost 19% of Spanish GDP but there is a widespread feeling that the central government takes much more than it gives back.
  This sense of injustice fuels the independence campaign, especially since Mr Mas was rebuffed by Mr Rajoy when he asked for greater fiscal powers in 2012.
  Catalan became the joint official language along with Spanish after the return to democracy. But in recent years Spain has challenged its status as the first language of instruction in schools.
  It is difficult to calculate how much more Catalans contribute in taxes to Madrid each year than they get back from investment in services such as schools and hospitals because of Spain's complex system of budget transfers.
  However, Spanish government data from 2011, published only this year, show the region paid â‚¬8.5bn (Â£6bn) more than it got back. According to the Catalan government, the discrepancy was closer to â‚¬11.1bn - the equivalent of nearly half of Catalonia's budget for this year.
  Meanwhile, state investment in Catalonia continues to drop: the 2015 draft national budget allocated 9.5% to Catalonia - compared with nearly 16% in 2003.
  While some Catalans may accept their tax money being used to help ailing southern regions like Andalusia, there is a perception that their own public services are being underfunded at the same time.
  On the other hand, Spanish unionists argue that taxpayers in the Madrid region pay out even more.
  Scotland's 2014 independence referendum inspired Mr Mas and his supporters, despite the No camp's victory. Unlike Catalans, Scots were allowed a legitimate vote on their future.
  With its own language, a recorded history of more than 1,000 years as a distinct region, and a population nearly as big as Switzerland's (7.5 million), Catalonia lays a strong claim to nationhood.
  It also happens to be a vital part of the Spanish state, locked in since the 15th Century, and subjected periodically to repressive campaigns to make it "more Spanish".
  According to the most recent Catalan government data, nearly one in five adults living in Catalonia today was born in a different part of Spain, while under Franco, the proportion was even higher, at 36.7% (figures for 1970).
  Depending on who you ask, Barcelona today is the capital of Catalonia - or Spain's second city.
  Catalonia profile - Timeline
  Catalonia is worth much more to Spain economically than Scotland is to the UK.
  So whoever runs Spain after the December general election will want Catalonia to remain part of it.
  But momentous changes may be afoot in the country's national politics and it is not yet clear who will win.
  The Popular Party may prefer to stick to the legal route to keep the secessionists in check.
  The opposition socialists are against independence but have mooted a constitutional reform that would grant the region more powers. The anti-capitalist Podemos movement supports Catalonia's right to a referendum.
  The rise of new parties also complicates the picture in Catalonia.
  The centre-right Citizens (Ciudadanos) party, which was born in Catalonia, has become the second force in Catalan politics, winning almost 18% of the vote. Notably, the party is firmly opposed to independence and is surging in the opinion polls nationally too.
  Independence campaigners argue the idea of a rich region like Catalonia being expelled from the EU is unthinkable.
  In a BBC interview, Raul Romeva of Together for Yes said that 7.5 million Catalan citizens who were already part of the EU could not be removed from it. However, the region would likely have to apply to become a member from scratch, as it would need to be recognised as a state by all 28 existing members.
  The EU's executive body, the European Commission, has tried to stay out of the debate, insisting that is not for the Commission to take a position on a member state's constitutional arrangements.
  But European leaders have backed the stance of the Madrid government.
  UK Prime Minister David Cameron has warned that an independent Catalonia could end up outside the EU and would have to "take its place at the back of the queue" if it sought to rejoin. And Germany's Chancellor Angela Merkel has said she stands with Mr Rajoy on respecting "national law".
target: Pro-independence parties in Spain's richest region, Catalonia, are pushing ahead with a historic plan for an independent state within 18 months, and the national government in Madrid is fighting back.