This is what Italians are actually voting on in Sunday's crucial referendum

Italy's upcoming constitutional referendum, in which the country will vote on a series of changes to the way Italy's institutional frameworks are structured, is one of the biggest political events in Europe in 2016.

Much has been written about what the referendum's outcome could mean for Europe's already uncertain political environment, particularly the future of Prime Minister Matteo Renzi and what the impact a "no" vote could have on the populist movement across the continent.

If Renzi's "Yes" campaign loses, he is expected to resign, leading to a new government. A "No" vote will also likely give the populist Five Star Movement a substantial boost, and signal a further victory for a global populist political insurgency that has already helped cause Brexit and the election of Donald Trump to the US presidency.

However, while the wider political implications of the referendum are largely understood, exactly what Italians are voting on has not been as broadly discussed. Business Insider has rounded up some of the crucial points about the referendum.

How does Italian parliament currently work?

To understand the referendum, we need some background on the current structure of the Italian parliament. Italian politics operates under what is known as a "symmetric bicameral legislature." Here's what that means:

• Essentially, there are two chambers - much like the UK House of Parliament - with a lower house, called the Chamber of Deputies, and an upper house, the Senate of the Republic.
• Both chambers are elected for five years, and elections are held simultaneously.
• The Italian government is accountable to both chambers, and must retain the confidence of both to stay in power.
• Any new legislation has to be passed by both chambers, and text for bills must be exactly the same. That means whenever either chamber makes even the tiniest amendment to proposed legislation it must go back to the other.
• The process, known as "navetta parlamentare" or parliamentary shuttle, is one of the things that Renzi's reforms seek to address.

What are the most important reforms?

The reforms are fiendishly complicated, but are effectively designed to try and streamline and make more efficient Italy's legislative process. Here are some of the key points:

1. One of the main proposed reforms would fundamentally alter the role of the senate, meaning that the government would no longer need to have the senate's confidence and that the upper chamber would not be able to pass a motion of no confidence against government.
2. The composition of the upper house would also be changed significantly. Currently, there are 315 senators in the chamber. If Renzi's reforms pass, there will instead be 100 senators, with 95 elected by regional councils across Italy, and five appointed on a fixed seven-year term by Italy's president. Of the 95 senators, 74 will be regional councillors, and 21 would be regional mayors.
3. Senators won't be paid, but will be granted parliamentary immunity.
4. The changes will effectively mean that Italian politics turns into a unicameral system for the majority of government business, but will remain bicameral for some types of legislation, including European policy, alongside constitutional laws and election laws.

A changing role for the president

The role of the Italian president, currently Sergio Mattarella, is also at stake in the referendum.

Italy's president largely undertakes ceremonial duties, but is an important figure, especially when things like a government collapsing or other crises strike Italy. This happens pretty frequently (Italy has had more than 60 governments since the Second World War.)

Under Renzi's reforms, the way the president is elected will change. There are usually up to six rounds of voting when Italy elects its presidents. As it stands, the president needs to obtain an absolute majority after the third round of ballots, but under the new reforms, they will need to pull in 60% of the vote from the third round.

Other measures

The above reforms are the most important being tabled, but other smaller changes are also proposed. These include:

• Only the Chamber of Deputies would be allowed to declare a state of war in the country. Currently, both houses must ascend to entering a war. An absolute majority would be required in the chamber, however.
• Government would be able to deploy a so-called "supremacy clause" to overcome the senate and vote on regional matters citing national and economic interests.
• Certain legislative powers currently in the hands of Italy's regions would shift to Rome, with infrastructure, transport, and energy coming under central government's control.

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