Confused about what is going on in Greece? Here's a Q&A to help you unravel it. Q: What's the background?The left-wing Syriza government, elected in January, promised to end austerity measures imposed on Greece by its creditors - the International Monetary Fund, the European Central Bank and the European Commission - in 2010. But Syriza has said it wants to remain a member of the eurozone.Q: What has happened since?Five months of negotiations have descended into acrimony. The creditors demand economic reforms, tax hikes and spending cuts, in return for handing over the bailout money Greece needs to keep repaying debts. Syriza is unwilling to compromise on key election promises, saying to do so would hurt pensioners and workers.Q: Why on Friday was a referendum called?After a week of talks Prime Minister Alexis Tsipras said he was faced with an ultimatum by lenders. He called the vote to allow Greeks to decide whether the lenders' terms should be accepted.Q: What do the creditors want?Sticking points are the level of VAT increases and pension cuts, needed next year. Lenders want 23%VAT on processed foods, more tax on hotels and restaurants, and an end to tax exemptions for Aegean islands. They also want the retirement age to be raised to 67 by 2022, and defence cuts.Q: Which side is the government on in the referendum?Tsipras appears to back a "No" vote. Prominent party members, particularly the extreme left, call for a rejection of euro austerity.Q:Is everyone behind the referendum?No. The snap decision has divided Greece. Socialist MP and former foreign minister Evangelos Venizelos said calling it constituted a "coup".Q: Will it definitely go ahead?Opposition parties might boycott the referendum. To be valid, there must be a minimum 40% turnout. The current bailout expires tomorrow. Tsipras has asked for a few more days, until after the referendum, but eurozone finance ministers will not consider it. An extension would require ratification by the other 18 national parliaments of the eurozone. There is no political will to give Greece leeway after the surprise poll.Q: How are Greeks likely to vote?Opinion polls show around 70% backing euro membership. But asked if they would stay in under the lenders' conditions, this falls to 55% to 60%. The wording of the final deal is crucial.Q: Does a "No" kick Greece out of the euro?Not quite, as the vote is not a clear in/out on membership. But the government might see rejection as a mandate to default on debts, which would bring ejection.Q:What happens if they vote "Yes"?That will probably prove to be the end for Tsipras. With no clear opposition party, a national unity government could be formed.Q:Could the banks collapse before the vote?Very possibly. Greece's banking system is being kept alive by emergency money from the ECB. After the referendum was announced, Greeks rushed to ATMs to withdraw money, putting bank solvency in doubt. If the bail-out is not extended, ECB rules let it pull the plug on Greece.Q:Will the gamble pay off for Tsipras?In calling for a vote, he took Greece's fate out of his own and creditors' hands...