Sony’s PlayStation Network and Microsoft’s Xbox Live are both still recovering after being down for many users Christmas Day, while a hacking collective known as “Lizard Squad” began claiming credit for the outage.

So who is the Lizard Squad, and is it really responsible for taking down the world’s top online gaming networks? Here’s what you need to know about these hackers.

MEET THE LIZARD SQUAD

The Lizard Squad began showing up more on the online hacking radar this year, largely by attacking gaming networks. This wasn’t the first time the group targeted Sony and Microsoft’s gaming networks. It claimed to have hit the PlayStation network in August and Xbox in early December, as well as several others such as RiotGames’ League of Legends and Blizzard’s Battle.net.

Apparently in conjunction with those hacks, the group pulled off some fairly serious pranks. In August, while Lizard Squad was hacking the PlayStation network, the Twitter account associated with the group tweeted out a bomb scare, forcing an American Airlines flight to make an emergency landing. On board was Sony Online Entertainment President John Smedley. The incident put Lizard Squad squarely in the sights of the FBI, several news organizations have reported.

Around the same time, that Twitter account (which has since been suspended) also claimed to have “planted the ISIS flag” on Sony’s servers.

SHOULD WE BE WORRIED?

Tweeting a bomb threat is a pretty serious federal crime. But for the most part, Lizard Squad’s tactics have amounted to pranks rather than public safety threats. Most hacking analysts doubt the group has anything to do with ISIS.

But when it comes to hacking, Lizard Squad seems to know what it is doing. One network analyst warned this week that the group is “not to be trifled with.”

“Let me say this about Lizard Squad,” said Dan Holden, director of research at the IT analysis firm Arbor Networks. “My personal opinion is, those guys know what they’re doing, and if they’re coming after you, you’re going to have a bad day.”

Lizard Squad’s apparent weapon of choice is Distributed Denial of Service attacks, or DDoS attacks, which overwhelm servers with massive amounts of fake traffic, rendering them inoperable.

But as the bomb scare and ISIS flag incidents show, the group appears to have greater ambitions than just carrying out a bunch of DDoS hacks. But as with everything in the hacking world, it’s hard to know whether Lizard Squad is responsible for these hijinks or whether they are just taking credit for the work of others.

WHY ARE THEY DOING THIS?

As with many hacking organizations, Lizard Squad’s motivations are often described as “for the lulz” – hacker-speak for “because it’s fun, or funny.” Over time, its strategy has evolved a little. The group now targets gaming companies, specifically to expose lax security practices, members claimed in an apparent interview with tech news site WinBeta. By disrupting networks like Xbox Live, its members say, they force companies to improve user protections.

But there is also evidence of pure self interest: Lizard Squad agreed to withdraw their Christmas Day attack on gaming systems in exchange for an offer of lifetime accounts to the online encrypted file hosting service Mega which was created by founder Kim DotCom, according to reports.

Another group, calling itself “Finest Squad” claims to be playing interference, DDoS-ing Lizard Squad servers in an attempt help the gaming networks return to normal service. The group has also posted a site featuring alleged information on the digital footprint and identities of Lizard Squad members.

WHEN CAN I GET BACK TO PLAYING MY XBox?

On Christmas morning, Microsoft and Sony customers began reporting connection issues as many with new Xboxes and PlayStations struggled to get online. That trouble continued on Friday morning.

Both companies acknowledged the disruption in service, but did not confirm whether the outages were the result of an outside attack.

The services themselves do not appear to have been compromised, and no personal information seems to have been leaked. What Lizard Squad claims to have done is simply clog up the service with its DDoS attacks.

By Friday, conflicting reports emerged about what Lizard Squad was up to.

XBox’s networks appeared to be back up, but moving slowly. PlayStation’s was still struggling to get online, but it was unclear whether this was because of the number of people trying out their new Christmas presents, or because of the continuing work of Lizard Squad or some other hacking group.

One Lizard Squad twitter account credited Kim DotCom’s offer of free accounts for convincing them to release the gaming networks. But another account said it would continue its attacks on PlayStation’s network unless its account got 1,000 retweets, among other requests.

Of course, it’s hard to know whether these tweets are authentic, or whether Lizard Squad was responsible for the attacks. It’s just the way the hackers want it.