Some governments have “kill switches” that can turn off the internet in their country. Egypt did this during the Arab Spring uprising in 2011 to make it more difficult for protesters to coordinate their activity. Turkey and Iran have also shut off internet connectivity during protests. China is rumoured to have a kill switch of its own. And American senators have proposed creating one in the US as a means to defend the country from cyberattack. Building a kill switch is not easy, however. The larger and more developed the country, the harder it is to shut down the internet completely there are simply too many connections between networks both inside and outside national borders.
Rachel Nuwer, 'What if the internet stopped working for a day?', BBC