Open Access journals with article processing charges (APCs) are an attempt to change the way scholarly journals work, allowing authors or their institutions to pay once the article had been peer reviewed and accepted. The move away from subscriptions would allow anyone in the world to freely read the scholarship presented.
This business model, linked with the ability to create professional-looking web pages cheaply, gave scammers an opportunity. They create a fake journal website, solicit articles from researchers via email, accept those articles immediately without any peer review, collect the APC, and post the article. Fake conferences also follow this model.
Much has been written about predatory publishing; what follows is a small sample.