Why is the switchover happening?

Digital is now the best technology for broadcasting TV. To make sure everyone in the UK can receive it, the signal needs to be available for free everywhere, ideally through a normal aerial. At present, around 74% of households are in areas where this is possible. Digital signals for the rest of the country can only be switched on when the existing analogue ones are switched off. After switchover almost everyone (at least 98.5%) will be able to receive digital TV  through an aerial.