In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by sharing findings from research with readers. They are normally specialized based on discipline, with authors picking which one they send their manuscripts to. Content Scientific journals There are thousands of scientific journals in publication, with one estimate from 2012 indicating that there were 28,100 that were active, and many more have been published at various points in the past (see list of scientific journals). Most journals are highly specialized, although some of the oldest journals such as Science and 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 (or trade journals), they are actually quite different. Among others, scientific journals' papers' authors are experts who must cite everything (and how they have a works cited page). They also deal with research, and are peer reviewed. Meanwhile, trade journals are aimed at people in different fields, they focus on how people in them can do their jobs better, they cover information related to work, and they include tips and advice for improving performance. Also, they are not scholarly. Articles in scientific journals Articles in scientific journals are mostly written by active scientists such as students, researchers, and professors instead of professional journalists. Their intended audience is others in the field (such as students and experts), plus their content is more advanced and sophisticated than what is found regular publications. They have different purposes, depending on the type. Ones with original research are meant to share it with others in the field, review articles give summaries of research that has already been done, and perspective articles give researchers' views on research that their peers performed. Each article has several different sections, including the following: The title; Information about the author(s); The abstract, which is a one-paragraph summary of the article; The introduction, including a background, why the research was done, research on this topic that has been done before, and (possibly) a hypothesis; The methodology or method, which includes the way the research was done, details concerning the study's sample, measures for assessment, and the procedure; Findings or results, which summarize what the study found;