This is not the first time Jobs has publicly criticized Flash, but the statement was his clearest, most definitive—and longest—on the subject.

In his 1,685-word “Thoughts on Flash,” Jobs laid out his reasons for excluding Flash—the most widely used vehicle for videos and games on the internet—from Apple’s blockbuster handheld devices.

He cited “reliability, security, and performance,” and the fact that Flash was designed “for PCs using mice, not for touch screens using fingers” as some of the reasons Apple will continue to keep the program off its devices.

But he said the most important reason is Flash puts a third party between Apple and software developers. In other words, developers can take advantage of improvements from Apple only if Adobe upgrades its own software, Jobs wrote.

Adobe representatives did not have an immediate comment on April 29. But in a March 23 conference call, President and CEO Shantanu Narayen said his company is “committed to bringing Flash to any platform on which there is a screen.”

That certainly includes Apple’s devices, and Narayen said at the time the Flash ban “has nothing to do with technology.”

“It’s an Apple issue, and I think you’ll have to check with them on that,” he said.

McGoodwin of Study.net said his company would “adapt accordingly” to Apple’s Flash decision, partly because the eReader has gained almost immediate traction in higher education.

“We’re committed to supporting [the iPad],” he said. “We will make it possible for students to access our content … whether they use an iPad or not.”

Adobe has owned Flash since buying its creator, Macromedia Inc., in 2005. Flash is one of the slew of software tools Adobe sells to professional designers and web developers as part of its Creative Suite software package, which also includes Photoshop, Illustrator, and other programs, and brings in more than half of Adobe’s revenue. Adobe benefits from Flash’s wide use, because it means web developers will keep buying the tools they need to create Flash content.

Although many web sites use Flash to display videos, animation, and internet ads, this might change in the years to come. HTML5, a new web standard—that is, a way to create web pages—will have built-in support for video and audio files.

But it could take as long as 10 years for HTML5 to be fully adopted, said Sheri McLeish, an analyst with Forrester Research. What Apple is banking on is that HTML5 will eventually win out, making Flash obsolete.

Material from the Associated Press was used in this report.