Articles give practical information to people in an industry.
Some illustrations are included, usually charts, graphs, etc.
Authors use jargon of the industry.
Primary, Secondary, Tertiary
Primary sources are original materials on which other research is based. It includes documents such as poems, diaries, court records, interviews, surveys, fieldwork, and some newspaper articles. It also includes research results generated by experiments, which are published as journal articles in some fields of study.
They are also sets of data, such as census statistics, which have been tabulated, but not interpreted.
Secondary sources describe or analyze the primary sources.
Examples of secondary sources include: dictionaries, encyclopedias, textbooks, and books and articles that interpret or review research works.
Examples of tertiary sources includes indexes and abstracts which serve to locate secondary and primary sources. An index will provide a citation which fully identifies the work: author, title of article, title of journal or book, publisher and date of publication, For a journal it will include the volume, issue and pagination. An abstract is a summary of the work being cited. Many indexes and abstract are available now online.