Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.
YouTube, of course, is the stratospherically popular video-sharing Web site where people post short videos of every description: funny clips from TV, homemade blooper reels, goofy short films, musical performances, bite-sized serial dramas, and so on. YouTube's fans watch 100 million little videos a day.
Of course, you already have a Web browser on your iPhone—Safari. Why does the iPhone need a special YouTube program?