What Exactly Happened to Knock So Many Sites Offline?

The cyber attack that brought down some major websites Friday is the "difference between taking a drink of water and being waterboarded," one cyber security expert told NBC News.

"When criminals manipulate web traffic to point toward a particular site in a short period of time, it overwhelms it," said Robert Siciliano, CEO of IDTheftSecurity.

Related: Massive Cyberattack Knocks Out Major East Coast Websites

What kind of attack was it?

Friday's attack was a DDoS, or distributed denial of service, and brought down a number of popular websites including Amazon, Twitter and Spotify.

How does it work?

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A DDoS is typically pulled off with networks of "zombies," which are computers compromised by attackers that can be used to flood a server, Siciliano said.

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FOR SUBSCRIBERSAbdul El-Sayed tries to woo MAHA voters as Democrats seek inroads with RFK’s supporters

FOR SUBSCRIBERSKratom-like substances are popping up in a typically benign supplement

FOR SUBSCRIBERSGOP super PAC increases its spending for Sen. Jon Husted in tough Ohio race

FOR SUBSCRIBERSRecords reveal tumultuous marriage between slain New York Times executive and wife

FOR SUBSCRIBERSFrom clean energy warrior to ‘wall of shame,’ James Talarico reverses on a fossil fuel money pledge

FOR SUBSCRIBERSCongressional staff planned official trip with luxury stops in Italy and France weeks before election

FOR SUBSCRIBERSA harrowing ordeal aboard an Israel-bound plane

FOR SUBSCRIBERSOpenAI CEO Sam Altman to skip congressional hearing on rogue AI agents

FOR SUBSCRIBERSKey DOJ lawyers departed Trump ‘grand conspiracy’ probe amid pressure to produce, source says

FOR SUBSCRIBERSTrump’s new AI chatbot often links to a site launched under Clinton 26 years ago

FOR SUBSCRIBERSAt MAHA summit, industry CEOs the movement once vilified take the stage

FOR SUBSCRIBERSThis Paralympian has two goals: Win medals and give away $500,000 to her teammates

FOR SUBSCRIBERSCornell rape allegation spotlights stringent New York state laws that have long drawn criticism

FOR SUBSCRIBERSThe debate over AI’s future rages on both coasts

FOR SUBSCRIBERSDecades-old march dispute reignites in Northern Ireland, threatening political crisis

Who was behind it?

It's unclear who orchestrated the attack and whether it could possibly be state sponsored. Siciliano said pulling off this level of attack takes some cyber savvy.

"Not everybody can perform a DDoS attack, but you could actually pay someone to do it, so anyone can with the right resources," he said.