Fibre optic internet runs via special glass cables under the ground. It doesn't require the copper wires used for your landline, like standard ADSL broadband, so it's faster and more stable. Currently, the 'up to' speeds for fibre optic broadband max out at around 100Mbps, but BT and Openreach have tapped into a new 300Mbps connection that should be available from selected internet service providers soon.