A key part of the internet's infrastructure was hit by a series of attacks in the past 24 hours, causing major services such as Netflix, Twitter, Spotify, Airbnb and news sites such as The New York Times to be inaccessible for many users.

The attacks targeted Dyn, a company that helps people connect to websites, with a huge amount of traffic in an attempt to knock the service offline, according to Dyn's director of internet analysis, Doug Madory.

The first digital assault appears to have started around 7.10am New York time on Friday in the US, and Dyn said it was resolved at roughly 9.20am. A second attack began around 11.50am, according to the company. And a third attack occurred in the afternoon.

The service that Dyn provides is called the Domain Name System or DNS. It works sort of like a phone book for the internet — translating URLs into the numerical IP addresses for the servers that actually host sites so your browser can connect to them.