Fox News' two-hour GOP debate was the most-watched primary debate in history, according to Nielsen, with more than 10 million viewers tuned in. But off-screen, many more witnessed Donald Trump sparring with host Megyn Kelly and other highlights, as well as behind-the-scenes action. Snapchat, the popular photo- and video-sharing app known for its millennial hook, drew in millions more views with its GOP “Live Story.”

The company declined to provide exact metrics but a typical feed generates 10 million to 20 million unique views, including from this Twitter user: “Following the debate via snapchat #noTVproblems #GOPDebate,” Hannah Hyslop tweeted Thursday night as the first Republican presidential debate aired on Fox News Channel.

Snapchat’s team created a collection of photos and videos of the debate that was available in a public stream to all Snapchat users in the United States (Snapchat reports that 60 percent of 13- to 34-year-olds in the U.S. have the app). The stream, called “First GOP Debate,” went live shortly after 7 p.m. EDT, two hours before the main event.

Snapchat stitched together scenes from attendees in Cleveland. Some chosen submissions came from the politicians, or their handlers. At launch, the feed showed videos from Wisconsin Gov. Scott Walker, Ohio Gov. John Kasich and former Florida Gov. Jeb Bush. Overlaid on the footage were stickers that displayed the candidates’ names, most recent position, age and hometown.

Photo: Snapchat Screenshots

Snapchat’s team constantly updated the stream by taking away some content and inserting other content. For example, the feed would at times be more than 3 minutes in length and then at next click would last only 30 seconds. The constant change and fluidity is a way Snapchat makes its content engaging for users, pulling in more views from its reportedly highly engaged audience.

Snapchat’s head of news, Peter Hamby, who joined the company in April after serving as a national political reporter for CNN, provided commentary into what was happening in the debate.

When International Business Times sought a comment from Snapchat after the debate, a Snapchat representative wrote, “We typically let the stories speak for themselves.”

Storytelling via photo and video is one way the company has grown from much more than just the creator of a one-to-one messaging app. Snapchat launched its first Live Story in June 2014 and now claims it's the app’s most popular feature.

S/O to the GOP debate on snapchat live. Made me feel like I was there. — Christina Faeth (@seafaeth) August 7, 2015

imagine being a teenager and actively engaging in politics for the first time ever through this GOP debate snapchat story — William Gruger (@wGruger) August 7, 2015

Loved watching every second of the GOP debate @Snapchat story. Raw stuff you'd never see anywhere else. pic.twitter.com/stGVOeJxiH — Nirav Savjani (@savjani) August 7, 2015

After the event went off-air, the GOP story was still accessible on Snapchat. That longevity allowed users to not only view the stream during the debate’s live telecast but also use it as a recap of Thursday's event. Snapchat’s Live Stories typically last 24 to 36 hours.

In addition to the lighthearted photos and videos, the “First GOP Debate” story also had video ads. Kasich’s super PAC, New Day for America, paid for a 10-second spot supporting the candidate. The Foundation for a Secure and Prosperous America created a video that argued against Kentucky Sen. Rand Paul’s support of the Obama administration's Iran nuclear deal. Environmental group NextGen Climate secured a spot for an ad calling for action on climate change.

Beyond the videos, digital firm Harris Media created a sponsored filter -- a sticker that read “How I Feel About The Bad Iran Deal” -- for its client Secure America Now.

“Filter went amazing,” Harris Media founder Vincent Harris wrote in an email. “Biggest surprise was the way in which it bled over into other mediums … We were seeing the filter on Twitter, Facebook, and Instagram, it was great.”

Secure America Now bought a Snapchat filter ad for the debate pic.twitter.com/OYbAHlafLC — Hunter Schwarz (@hunterschwarz) August 6, 2015

While Snapchat does not have a website that allows for easily embedding and sharing content to other sites, users commonly take screenshots of what they see and can post those to other networks. Ad buyers like Harris Media are notified of the number of screenshots. That organic network has proven intriguing for politicians, companies and users.

Snapchat, which is privately held and does not disclose its financial results, also plays into the virality generated by users. The company did not post on its Twitter account or issue any other formal announcement for the upcoming GOP story. Nor has it retweeted any coverage via Twitter -- at least not yet.

Final numbers have yet to be released, but Harris wrote in an email that the "engagement has so far exceeded my expectations and will become a staple in my clients' media plans.”