Amazon Web Services (AWS) had a bad day. That's how the boss of another big US tech firm Cloudflare put it – probably feeling very relieved that Monday's outage, hitting over 1,000 companies and affecting millions of internet users, had nothing to do with him.

Amazon Web Services experienced DNS resolution issues on Monday morning, taking down wide swaths of the web—and highlighting a long-standing weakness in the internet's infrastructure.

The outage underscored a central trade-off of cloud computing: while it lets businesses deploy global services without maintaining vast infrastructure, it concentrates risk. A problem in a single region—like Northern Virginia—can cause widespread, simultaneous outages for unrelated companies worldwide.

Maybe we rely on Amazon Web Services a little too much. Thousands of sites, apps, and services went dark Monday morning. Here's why.

Since a large portion of the internet depends on AWS, the outage cascaded across major firms in disparate industries, leaving some people unable to access airline information or make everyday purchases, Qi Liao, a professor of computer science at Central Michigan University, told ABC News.

Get our top stories delivered straight to your inbox.

A major outage caused by an issue at Amazon Web Services affected hundreds of websites, games and apps, including Amazon, Snapchat, Fortnite and several banks. Amazon says it fixed the underlying problem but a full recovery will take longer.

BBC Sport's Ask Me Anything team explains why the Amazon Web Services global outage affected Brentford's win over West Ham