PLOS ONE

PLOS One is a scientific journal. It is an interdisciplinary journal. That means it prints scientific papers about almost any kind of science instead of just one. It prints papers about engineering, biology, the social sciences and humanities, for example science papers that talk about art. As of 2017, it was the largest scientific journal in the world by number of articles printed per year.
"PLOS ONE" is designed for research scientists are the primary audience for the journal, but ordinary people read it as well. Because of this, articles are written and edited to make them understandable to scientists in other fields and any educated person. 
"PLOS ONE" is published by the Public Library of Science. PLOS also publishes "PLOS Biology", "PLOS Medicine" and other journals.
Scientists must pay a fee to publish in "PLOS ONE", sometimes as much as US$1695. But then the study is available for people to read without paying a fee. It is not behind a paywall.
"PLOS ONE" can publish 20,000 scientific papers in one year. That means sometimes it publishes bad papers by accident. In 2016, "PLOS ONE" published many retractions, which means it said publicly that some of its papers were bad, said how they were bad, and said it did not believe in them.