The Spanish region of Catalonia is set to hold a referendum on independence on October 1.

The single question facing voters, "Do you want Catalonia to become an independent state in the form of a republic?", has generated many more.

Why does the referendum matter?

Catalonia, an area in northeastern Spain of 7.5 million people, accounts for 15 percent of Spain's population and 20 percent of its economic output.

About 1.6 million people live in Barcelona, Catalonia's capital, which is a major tourist destination.

Sunday's vote will be the region's second referendum on independence in three years.

For more: Exclusive interview with Catalan leader Carles Puigdemont

The previous ballot, a non-binding vote in November 2014, returned an 80 percent result in favour of an independent Catalan state. However, less than half of the 5.4 million eligible voters participated.

The Spanish government rejected the Generalitat's, Catalonia's regional government, proposal to hold a binding ballot on the grounds that it was unconstitutional. They take the same position on Sunday's vote.

Who can vote, will vote, and how?

Only Catalan residents of voting age are entitled to participate in the referendum.

Up to 85 percent are in favour of holding the referendum, according to a poll conducted by El Periodico de Catalunya, a regional daily newspaper.

However, only about 41 percent said they intend to vote "Yes" to independence when asked in June of this year by the Centre for Opinion Studies, the regional government's polling body.

A number of pro-union Catalans are expected to boycott the vote, on the grounds that the referendum is illegal.

Lluis Orriols Galve, a professor of politics at the Carlos III University of Madrid, told Al Jazeera that, despite expected disruption from Spanish authorities, many will be able to take part in the vote.

"The government will have big difficulties stopping the referendum in the territory, the state simply cannot control the whole region, but they will try to prevent it taking place in key areas such as Barcelona," he said.

Ada Colau Ballano, Barcelona's mayor, has reached an agreement with the regional government to allow voting in the city, despite opposing independence herself.

Why independence? Or why not?

Catalonia has a distinct history, culture and language.

First referenced in the 12th century, a defined region of Catalonia had existed for more than 250 years before it joined Spain during the country's formation in the 16th Century.

As such, identity plays a large role in the debate surrounding independence.

Under the military government of Francisco Franco, from 1939-1975, Catalan culture was suppressed.

Symbols of Catalan identity such as the castells, or human towers, were prohibited and parents were forced to choose Spanish names for their children.

The Catalan language (also spoken in Valencia and the Balearic islands) was also restricted, said Sergi Mainer, a lecturer in Catalan culture at the University of Edinburgh.

"With Franco Catalan was banned publicly, publishing was controlled under censorship, after the coming of democracy the only official language was Castilian," he told Al Jazeera.

"There was repression everywhere in Spain, but extra repression was felt in Catalonia."

However, support for independence among Catalans isn't universal.

"It's a false referendum and many think if there's no legal guarantee then it's better not to vote," Jorge Amado, president of Catalunya Somos Todos, a pro-union organisation for Catalans living outside the region (who aren't eligible to vote), told Al Jazeera.

"It's a manipulation. Manipulation of history, of the media, and of the Catalan people to promote this sense that Catalonia can't be united with Spain."

Why now?

The push for full autonomy appears to have gathered pace in recent years, most notably since Spain's 2008 debt crisis.

"In that moment, people in Catalonia demanded more self-government and control over what is done with their money," said Orriols.

Pro-independence supporters claim Catalonia, which is one of Spain's wealthiest regions, offers more financial support to Spain than it receives from the central government in Madrid.

Many view the region's strong economy as an indicator that it would be viable as a sovereign state.

READ MORE: Why Catalonia should be given a say on its future

Following a ruling by Spain's constitutional court in 2010, which stated there is no legal basis for recognising Catalonia as a nation, independence appears to have taken preference over reform for a portion of the region's population.

"Because of past experience, instead of demanding state reform, they started to support independence," Orriols said.

How is Spain reacting?

Spain's constitutional court ordered a suspension of the referendum the day after it was announced, following an appeal from the Spanish government who claimed the plebiscite would breach the country's constitution.

Spain's 1978 constitution decrees that the country is indivisible, and grants the national government exclusive power to hold referendums.

A majority of Spaniards outside of Catalonia, about 70 percent, oppose the referendum, according to Orriols.

READ MORE: The case against Catalan secession

Mariano Rajoy, the Spanish prime minister, has labelled the plan an "intolerable act of disobedience" and pledged to do everything in his power to prevent the vote from occurring.

Spanish authorities have arrested at least 14 Catalan officials, including Josep Maria Jove, the regional government's junior economy minister, in recent weeks.

Officials have also carried out a number of raids, entered local government offices and seized referendum campaign material, including some 10 million ballot papers.

"The government is fulfilling its obligation [to comply with the judicial ruling], and I have to say that we will continue to do so until the end," Rajoy said in a statement on September 20.

Carles Puigdemont, Catalan's president, accused Madrid of acting in a "totalitarian" manner, saying "we condemn and reject the anti-democratic and totalitarian actions of the Spanish state" in a televised address on September 21.

Spain's monarch, King Felipe VI, has declared the Spanish constitution "will prevail" over any attempt to break the country apart.

What powers does Catalonia already have?

In 1931, when Spain became a republic, Catalonia was given greater political autonomy within the confines of the state.

However, by 1939 its powers had been revoked following the Nationalists' victory in the Spanish Civil War.

Following Franco's death in 1975, Catalan autonomy re-emerged and flourished.

In 1979 a new Statute of Autonomy of Catalonia was issued, which restored the Catalan parliament.

Elections for the 135-member body were held the following year, on March 20.

The region, which forms one of Spain's 17 "autonomous communities", has its own police force and powers over affairs such as education, healthcare and welfare.

There are also provisions in place to protect Catalan identity, including joint language status for Catalan and Castilian and a law that requires teachers, doctors and public sector employees to use the Catalan language in their places of work.