There's a lot about coronavirus we still don't quite understand. And with the new pandemic, scientists are working hard to get a grips of what it means and what can be done to stop the spread.
As you may have hear in the governments daily coronavirus briefings, the likes of Sir Patrick Vallance, the governments chief scientific adviser and chief medical officer for England Professor Chris Whitty discuss something known as the 'R value'.
They usually refer to this when discussing the latest figures relating to coronavirus cases and deaths. For example, Prof Whitty said during Monday's daily press briefing that the lower the transmission rate of coronavirus – or R value – the "greater room for manoeuvre" there is for what lockdown measures