A neat summary and infographic from the Economist on the issues surrounding the Irish border in relation to Brexit.
What does the Irish border have to do with Brexit?
The invisible frontier has become the most complicated feature of Britain’s negotiations with the European Union. […]
For the past 20 years Britain’s political class has all but ignored Northern Ireland. Yet two decades after the end of the Troubles, the Irish question is back–and it is more likely than any other matter to derail Brexit.