Abstract: Some open access (OA) publishers charge authors fees to make their articles freely available online. This paper reviews literature on article processing charges (APCs) that has been published since 2000. Despite praise for diamond OA journals, which charge no fees, most OA articles are published by commercial publishers that charge APCs. Publishers fix APCs depending on the reputation assigned to journals by peers. Evidence shows a relationship between high impact metrics and higher, faster rising APCs. Authors express reluctance about APCs, although this varies by discipline depending on previous experience of paying publication fees and the availability of research grants to cover them. Authors rely on a mix of research grants, library funds and personal assets to pay the charges. Two major concerns have been raised in relation to APCs: the inability of poorly funded authors to publish research and their impact on journal quality. Waivers have not solved the first issue. Research shows little extension of waiver use, unintended side effects on co-author networks and concerns regarding criteria to qualify for them. Bibliometric studies concur that journals that charge APCs have a similar citation impact to journals that rely on other income sources.