Apple announced Thursday that its iTunes U offering has surpassed 1 billion downloads, as online education becomes more accepted at schools in the United States and more popular worldwide.

ITunes U offers free educational content from colleges, libraries, museums and more that can help professors create materials for their courses, which can be offered to students using the same platform.

For example, Stanford University in Palo Alto, Calif. — which offered the first publicly available iTunes U site after joining Apple for the pilot project in 2004 — offers lectures from its courses, as well as course materials, faculty presentations, event highlights and more on the service. Apple singled out Stanford in its news release for being one of two entities to produce more than 60 million downloads on its own.