Yahoo has confirmed 500 million users had their personal details stolen after a security breach.

The internet giant said they were currently investigating the "state-sponsored" attack, which they claimed took place in 2014.

They advised customers to "change passwords and security questions and review your accounts for suspicious activity."

Bob Lord, Yahoo's chief information security officer, said: "An increasingly connected world has come with increasingly sophisticated threats. Industry, government and users are constantly in the crosshairs of adversaries."

But how do you protect yourself online?