ComiXology, a digital comics platform that launched in 2009, sold 4 billion pages of comics through its iPad app last year, earning it the title of most profitable non-game app for the iPod for the third year in a row. That figure shows a drastic increase in sales since the launch of ComiXology, which has sold more than 6 billion pages of comics total. CEO David Steinberger says the considerable growth is due not only to long-time comics lovers moving over to digital versions, but new, first-time comics fans.

“Steinberger suspects the shift to a newer and more diverse readership is due in part to the breadth of content ComiXology offers, which contains a wider range of material than most comics shops,” Wired reports. The app has more than 45,000 comics available from more than 75 publishers.

The other obvious reason for its popularity is its convenience compared with the now old-fashioned method of actually visiting a store to buy a physical copy. According to Wired, “the app’s guided-view technology automatically shifts from panel to panel as you tap, which can help new readers navigate the sometimes forbidding visual lexicon of a new medium.”

Perhaps due to the more easily accessible content, ComiXology is also seeing a growing number of female customers. By the end of 2013, about 20 percent of its customers were female, and generally younger than the average male customer.

“We’re finding that a larger and larger percentage of our user base — our new user base — is people who are buying comics for the very first time with us,” Steinberger told Wired.

The article notes that those customers, in turn, are making their way to brick-and-mortar comic shops. “Of the 20 percent of ComiXology customers who bought their first comics online in the last quarter 2013, 64 percent have begun buying print comics as well.”