In freezing weather in the snow-covered upper Midwest, up to 186,000 Americans are getting ready for the Iowa caucuses, the first step in choosing the next Republican presidential candidate

Given the state represents just 1.6 per cent of the eligible Republican voters in the US, you might ask why is Iowa such a big deal. Why is it called a “caucus”, and not a primary like many of the other candidate-selecting events in the next few months, and how does it actually work?