In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. Most journals are highly specialized, although some of the oldest journals such as Nature publish articles and scientific papers across a wide range of scientific fields. Scientific journals contain articles that have been peer reviewed, in an attempt to ensure that articles meet the journal's standards of quality, and scientific validity. Although scientific journals are superficially similar to professional magazines, they are actually quite different. Issues of a scientific journal are rarely read casually, as one would read a magazine. The publication of the results of research is an essential part of the scientific method; they generally must supply enough details of an experiment that an independent researcher could repeat the experiment to verify the results. Each such journal article becomes part of the permanent scientific record.
The history of scientific journals dates from 1665, when the French Journal des sçavans and the English Philosophical Transactions of the Royal Society first began systematically publishing research results. Over a thousand, mostly ephemeral, were founded in the 18th century, and the number has increased rapidly after that. (D. A. Kronick, "History of Scientific and Technical Periodicals," 2nd ed. Scarecrow, 1976)
These articles are frequently used in research and graduate education. Many classes are partially devoted to the explication of classic articles, and seminar classes usually consist of the presentation by each student of a classic or current paper. In a scientific research group or academic department it is usual for the content of current scientific journals to be discussed in journal clubs.
The standards that a journal uses to determine publication can vary widely. Some journals, such as Nature, Science, PNAS or Physical Review Letters, have a reputation of publishing articles which mark a fundamental breakthrough in their respective fields. In many fields, an informal hierarchy of scientific journals exists; the most prestigious journal in a field tends to be the most selective in terms of the articles it will select for publication. It is also common for journals to have a regional focus, specializing in publishing papers from a particular country or other geographic region.
Articles tend to be highly technical, representing the latest theoretical research and experimental results in the field of science covered by the journal. They are often incomprehensible to anyone except for researchers in the field and advanced students. In some subjects this is inevitable given the nature of the content.