Open Access

Open access (OA) "means free online access to research literature. OA literature is not only provided free of charge to scientists, scholars, teachers and students, but to anyone with an Internet connection.

"OA is compatible with copyright and does not require that content be placed in the public domain. In practice this means that the copyright holder consents to the unrestricted reading, downloading, copying, sharing, storing, printing, searching, linking, and crawling of the work. But the copyright holder can retain the right to block the distribution of mangled or misattributed copies, and/or the right to publish the work in a printed journal."

Source
Public Knowledge, "A Beginner's Guide to Key Concepts."