Articles are excellent for finding:
Articles can either be scholarly or non-scholarly in nature.
Articles in scholarly journals generally have been reviewed by an editorial board, have gone through some type of peer-review process, and are the in-depth, primary account of original findings written by the researcher(s) in their field of academic interest. Many but not all professional journals are peer-reviewed.
Articles in popular magazines, newspapers and trade publications on the other hand are written from a non-scholarly perspective. They are generally not peer-reviewed, favor a much more informal writing style, and often have no, or only very brief, bibliographies. Non-Scholarly articles can be helpful but it just depends on what your research needs are.
Scholarly articles can generally be identified by several features:
(This list was inspired by the various lists available on library websites, particularly that of Judith Downie at California State University San Marcos)
Two common ways to find scholarly journal articles:
1. Search an article database and then limit the search to scholarly (peer-reviewed or refereed) materials; or
2. Locate a journal and verify if it is a scholarly one by searching in Ulrich's Global Serials Directory.
If you are still unsure whether an article is scholarly or not, the best source to turn to is an expert in your field -- ask your professor.