The options on the table for the UK when it comes to that most contentious of issues.
It could even lead to a loss of low-skilled manufacturing jobs.
But it's not clear what proof of permanent right to reside will mean after Brexit.
The history of how the British fell out of love with seasonal farm work.
Can you visualize any number greater than 100? Migration experts explain why thinking about migrants en masse makes it difficult to address the nuances of each group's unique challenges.
A German culture scholar looks at how rising fear of terror and a week of violence has affected German media and politics. Will Germany's open refugee policies last?
Free movement will be at the heart of post-Brexit negotiations. But what is it?