Article processing charges (APCs) are fees that publishers charge authors to help finance a journal.
Lately, publishers have used them to make their publications available via Open Access (OA), the practice to make scholarly literature freely accessible online. Two major routes to make your work OA are either through "Gold OA" in a hybrid (mix of OA and subscription fee) or through a complete OA journal.
The Plan S Coalition sees it as a way forward, through "transformative agreements". More info at https://library.ust.hk/sc/qa-apc/.
It varies from publisher to publisher, and journal to journal. There is a wide range, and overall they are not small sums. Some examples (as of April 2019):
The pricing mechanism isn't transparent.
It depends. APC is optional with a hybrid journal. If you choose not to pay, your paper will still be published in that journal, but behind paywall, i.e. only subscribers can read.
Yes, they are. Often this charging model is criticized as double-dipping. Although some publishers claim they offset the subscription costs with the amount of APC they receive, it is hardly clear how they do it. With the business model of academic publishing, transparency is always a big issue.
In the US and Europe, some universities and funding agencies allow research grants to cover APC. In Hong Kong, RGC requires the Project Coordinator (PC) or Principal Investigator (PI) to make the final publications openly accessible immediately or no later than 12 months after publication, but there is no guideline on APC.
The Library launched an Open Subscription agreement with AIMS (American Institute of Mathematical Sciences) in 2023. It allows unlimited Gold open access publishing at no costs to authors in below three journals:
Key points to note:
HKUST Library has recently signed a "Transformative Agreement", also known as "read & publish" (R&P), with Cambridge University Press (CUP). This agreement means: