Q&A: Currency interventions

The world's biggest economies have got together to intervene in the currency markets for the first time in more 10 years.

What is currency intervention?

Why would governments want to intervene?

How does it work?

Does it always work?

What exactly is Japan's currency problem?

Why did the latest disaster make things worse for the Japanese currency?

Why did the G7 get involved?

How did the intervention work in practice?

When did intervention like this last happen?

So has this yen intervention worked?