Brexit for complete dummies

[Nannyplumbrocks]

Ok, I'm not British but of course Brexit is all over the news and almost impossible to ignore. I'm in Europe. Can someone give me a very very basic explanation of what Brexit is, what "deal" are they trying to figure out and just basically what the whole thing is about. And what has northern Ireland to do with it? Everything im reading is so bloody complicated and I'm lost.

Like many things it is quite complicated:
To settle an internal argument of the 'ruling' Tory government in late 2015 or early 2016, the Prime Minister instigated a referendum to take the UK out of the EU.
He expected that the country would say 'stay in' (remain) but due to interference and lies, narrowly lost the vote.
There had been no real plan about how much it would leave or indeed if it was possible to actually leave so it is a mess.
Making things far more complicated is the Belfast agreement regarding a 'border' with Ireland (an EU country) and Northern Ireland, part of the UK. With both being IN the EU the tensions which have raged for many hundreds of years over the 'border' were relaxed with a commitment that there must not be a physical border of any sort.
When/if the UK leaves the EU, unless there are agreements made regarding trade and movement of people there OUGHT to be a border. The EU have pledged to support the Belfast Agreement (Good Friday Agreement) but the UK government needs to find a way to satisfy having a border that mustn't exist.

This border and some of the other requirements are mutually exclusive and there is no obvious solution that is acceptable by a significant majority. Since the workings and relationship between the Prime Minister, government, the House of Lords and the House of Commons is a tricky mess in itself there is no clear pathway through it.
Europe has lost a lot of money, the UK has lost a lot of money and all will be worse off for decades.
I would recommend the Westminsterenders thread for detail and comment, but there is a lot to wade through.

The withdrawal agreement is stage one. We don't get to stage two without it. May is trying to get a withdrawal agreement through.
Stage two is where we get to do trade deals with the EU, our biggest market.
The NI border is a problem to this is because the Good Friday Agreement requires no border. However, the WTO rules can only apply if you have border control of your economic territory. It would allow a fudge set out in the draft withdrawal agreement. The fudge effectively means a border between us and Ireland in the Irish Sea. The DUP doesn't want a border in the Irish Sea because it , they think, is the slippery slope to unification with Ireland. For lots of reasons they don't want this.

May I tag on a 'dumb' question: When does Brexit start?

23.6.16, that was just the vote.

29.3.17: trigger date for Article50, but we are still members even now.

29.3.19: end of A50 period, start of transition (assuming A50 not revoked)

2023? whenever transition ends, if it ever ends

I reckon UK can't say we've left until transition is done. But should 29.3.19 be called the first day of having left? What do others reckon? How will we know when UK has left?

It starts on 29 March 2019. If we get a transition because we have agreed a withdrawal deal, it should be fully in place two years later. If there is a problem with the transition it might be extended and the border in the sea could kick in.
If we don't have a withdrawal deal we crash out.