It's a short, sharp period with rules and restrictions get much more strict, so there are fewer opportunities for covert 19 to spread.

What, exactly changes will vary by country.

It should mean that an area then sees are falling cases.

But how far they fall isn't clear, and it depends how strict the rules are and how much people stick to them.

It gets its name from the Breakers.

You see an electric circuits when there's a problem.

These breakers stop electricity from flowing, preventing bigger problems down the line.

In some places, they're called firebreaks, a reference to when firefighters clear land of all trees, plants and grass to try and stop the fire from spreading.

It's usually a two week period, but a circuit breaker could last longer.

The idea is that they buy time.

But what will governments do with this time?

Allow the health service to recover allowed time to improve contact tracing systems?

What steps are they going to take to ensure the problem doesn't come back again when the circuit breaker ends?