Most scholarly journals subject manuscripts to a rigorous review process in which independent experts (the "peers") are asked to read and critique the manuscript, and make a recommendation as to whether it should be accepted for publication.
In a double-blinded peer-review process, neither the author of the manuscript nor the reviewer(s) are aware of the identity of the other party.
This process is an important safeguard for the consumer of scientific and biomedical information, and is intended to prevent poorly conducted research from ever being published. Nevertheless, articles suffering from faulty research methodology, bias, and even fraud are still occasionally published.