As of when we're writing this article, Steam has apparently suffered a widespread service interruption that has taken down the service. Reports started hitting social media around 12pm EST that people were losing connections to multiplayer matches and that games were not loading properly to online networks from titles like Rocket League, CS:GO, and Dota 2. By 1pm EST, it was confirmed through multiple posts as well as sites like Down Detector that the service has suffered some kind of outage. Most people receiving a message the minute they load the program saying "Could not connect to the Steam network."
Normally in situations like this, whenever there seems to be some kind of network error, we generally refer to whatever the support social media page is for that company. But since Valve doesn't have one and the official Steam one hasn't been used in over three years, it's kind of hard for us to get any kind of confirmation about what's happening at the moment. In fact, Steam's primary Twitter hasn't posted a message in three days, so if you didn't launch the program today you wouldn't know there was an issue.
This could be about a dozen different things, but until the company actually sends out a message, everything we write after this is basically guesswork. We do know, however, based on other people's social media is that while it is widespread, it is not a complete outage of their service as others are still able to connect and play games. But depending on where you are in the world it's either just okay or running poorly. Hopefully, we'll get some kind of notice from the company on Twitter and we'll update you as this develops. Also, if any of the employees from Valve are reading, could you please start using the @Steam_Support account on Twitter again?