Article processing charge - Wikipedia
https://en.wikipedia.org/wiki/Article_processing_chargeJournals use a variety of ways to generate the income required to cover publishing costs (including editorial costs, any costs of administering the peer review system), such as subsidies from institutions and subscriptions. A majority of open access journals do not charge article processing charges, but a significant and growing number of them do. They are the most common funding method for professionally published open access articles.