Before a paper is published in a scientific journal, it is subjected to a process called “peer review.” The peer review system is designed to ensure that only high quality and reliable information is published in scientific journals.
In the first step of the peer review process, the author of a scientific paper submits it to the editor of a scientific journal. The editor chooses two or three researchers who are considered to be experts in the specific topic area covered in the paper, and submits the paper to those researchers. The researchers then independently conduct an impartial written review of the quality of the paper, and submit these reviews and any recommendations to the editor.
Based on the recommendations of the independent reviewers (and the editor's own review of the paper) the editor will make the decision to accept the paper for publication, reject it, or request revision and resubmission of the paper (at which point it will go through another cycle of review).
The peer review process has many limitations (e.g., it is slow, requires significant effort by all parties involved, and may not always be impartial), but it is considered essential for maintaining the quality of scientific journals and protecting the public from unwarranted claims based on poor quality science.