Hackers took over thousands of webcams around the world in one of the biggest internet attacks ever seen. They used a botnet comprising 100,000 'smart' devices, such as webcams, baby monitors, routers and digital video recorders to take down many of the world's most popular websites. The distributed denial-of-service (DDoS) attack, which took place in three waves on Friday 21 October, targetted Dyn, a US domain - name server (DNS). Visit Wikipedia for a full list of services affected by the attack: https://en.wikipedia.org/wiki/2016_Dyn_cyberattack
Millions of people used sites like DownDetector (http://downdetector.com) to check how widespread the problem was. The website shows live maps illustrating where people are unable to access certain sites. The attack was unusual because it used a botnet (called Mirai) made up of web-connected devices often collectively known as the 'Internet of Things' rather than computers. Security experts blamed default passwords that were easy to guess, urging people to change them.
It's not known who carried out the attack. A group called New World Hackers claimed responsibility, but this hasn't been confirmed.