Where are we at with Brexit? Your questions answered

EU leaders are meeting in the Austrian city of Salzburg over the next two days with plenty to discuss. What's it all about? Will Brexit finally be solved? What are the sticking points? Your questions are answered here - we hope!

:: Why Salzburg and what's the summit all about?

European leaders meet four or five times a year for summits - or European Councils to give them their formal name.

Most - the formal ones - are held in Brussels.

But "informal" summits are usually peppered into the calendar and are held in the country which holds the rotating presidency of the European Union.

It is a six month rotation and Austria is the current holder. It's an opportunity for countries to show off what they have to offer - hence beautiful Salzburg.

:: Is this a Brexit summit?

No. It was originally called to discuss another fire the EU is grappling with - migration.

Although the number of "irregular migrants" actually arriving in the EU from the Middle East and Africa is now back to levels seen before the 2015 peak, the number of people attempting to cross the Mediterranean and dying in the process is at record levels.

This is largely because charity rescue vessels are finding it harder and harder to operate because Italy will not let them dock.

The migration issue continues to fuel a political crisis across the continent.

So it will be a key focus (again) for EU leaders.

The president of the European Council, Donald Tusk, said in a letter to fellow leaders: "The quest to end the migration crisis is a common task of all the member states and EU institutions.

"If some want to solve the crisis, while others want to use it, it will remain unsolvable.

"I am hoping that in Salzburg we will be able to put an end to the mutual resentment and return to a constructive approach."

:: So what about Brexit? Will it be discussed?

Absolutely. To some extent the summit has morphed into a key Brexit staging post.

There won't be any formal conclusions or formal changes to the position of the EU - this is an informal summit and the rigidity of EU processes mean they cannot suddenly change course.

But there could be subtle indicators of positions being moulded.

:: Any key moments to look out for?

Yes - at the leaders dinner Theresa May will have time to state the UK position.

It is the first time that the leaders have all met as one since Britain's Chequers proposal (see below) was revealed back in July. So expect her to eyeball her colleagues with a detailed explanation of what that means.

There will be elements, no doubt, of what she said to German newspaper Die Walt this week: "We are near to achieving the orderly withdrawal that is the essential basis for building a close future partnership.

"To come to a successful conclusion, just as the UK has evolved its position, the EU will need to do the same.

"Neither side can demand the unacceptable of the other, such as an external customs border between different parts of the United Kingdom."

Towards the end of the summit the 27 remaining members of the EU will meet without Mrs May to discuss Brexit.

After that President Tusk and Mrs May will have a 10 minute meeting.

There she will hear, in private, what the 27 think, collectively, of her position. Immediately afterwards she will give a news conference.

:: Are the two sides really worried about there being a 'no-deal' cliff-edge withdrawal?

Yes. President Tusk made that very clear in his letter to EU leaders: "Unfortunately, a no deal scenario is still quite possible. But if we all act responsibly, we can avoid a catastrophe."

In my sideline chats, EU and UK diplomats are even more blunt. A "no-deal" by accident is unnecessarily possible - each blames the other's intransigence.

At the main summit - the remaining 27 EU leaders will meet without Mrs May but with EU chief negotiator Michel Barnier to discuss what they call the "state of play" of the negotiations.

This will be a chance to for the leaders get a reality check. Many have been dealing with other issues.

At this summit diplomats will put their leaders' noses in front of the facts.

They need now, urgently, to start thinking about what the future will look like because whether they like it or not, the UK will be the single most important country for the EU to deal with for the decades ahead.

:: Remind me again - what's the Chequers proposal?

The British position on Brexit has evolved over the months into the "Chequers Proposal" - it's Mrs May's attempt to please everyone in her party, in the country and in Europe and still deliver Brexit.

In July, at the Prime Minister's country residence - Chequers - the Cabinet agreed that their Brexit position to present to the EU was to maintain - after Brexit - common rules and existing borderless free trade in goods and agriculture, but not services.

It prompted the resignation of then Brexit secretary David Davis and foreign secretary Boris Johnson, both of whom thought the proposal did not deliver the Brexit people voted for.

And the EU side has consistently said Chequers isn't workable because it divides the integrity of the EU's single market by "cherry picking" the favourable parts of it.

:: What's holding things up?

There are two singular and distinct problems holding up the Brexit process.

The first is part of the divorce deal - the actual process of Brexit - and it's the "Irish backstop" problem.

Britain has committed to leaving the single market and the customs union.

By definition that means checks need to take place at hard borders between the UK and the EU unless or until some sort of mutual trade deal can be established.

It is known as the "backstop" because it is a fallback position that the EU insists must be "legally operable" in case no better arrangement in the form of a trade deal (which will take years) materialises.

But it is a problem on the island of Ireland where no one wants to see the a return of hard borders between the north and the south.

The EU's answer is for Northern Ireland to remain in the EU customs union. They say that checks can take place as goods pass between the British mainland and Northern Ireland and point out some agricultural checks already take place.

The UK says that is not possible because putting Northern Ireland in a separate customs zone breaks up the constitutional integrity of the United Kingdom.

The second problem relates to the framework for the future relationship. This needs to be ironed out and put in a formal text - a political declaration - as part of the Brexit process.

However the British Chequers proposal for the future relationship does not fly with the EU side.

They think it represents a partial customs union on goods but no customs union on services and no freedom of movement.

That, for Brussels, is cherry picking and undermines the integrity of the EU - other countries will want the same they fear and the whole single market/customs union project falls apart.

It is quite easy to find compromise on the political declaration or to fudge it and deal with it later, post-Brexit day. It's much harder with the Irish backstop which is more binary and immediate.

:: How's the relationship between the two sides?

Not great. The British perception that the EU side isn't budging despite significant compromises on their part is a source of huge frustration.

The EU is angered by suggestions in the UK, by the Brexit secretary and prime minister no less, that they won't pay the "exit bill" (which is actually a "signed up to" existing financial commitment) if there is no deal.

The EU was alarmed by Michael Gove's suggestion that whatever deal is done on the future framework, it can always be unravelled after Brexit day. (This angered the UK's own diplomats too as it undermines their negotiating position).

:: Still confused?

If you have other questions contact me on Twitter @Stone_SkyNews or Facebook (Mark Stone - Sky News) and I will try my best to answer them.