What are periodicals?
Periodicals are any type of publication that is published in a series, or periodically (hence the name). Things like newspapers, magazines, journals and newsletters are all periodicals, and the articles inside them are periodical articles.
Periodical articles are often the best sources for research, especially if your topic requires:
Periodicals cover events more quickly and concisely than books.
Books are usually better at giving thoughtful, historical information. Magazines and newspapers provide current, focused information, and specialized magazines and journals provide in-depth coverage.
Periodical articles are usually on specific topics
Many topics do not have entire books written about them (or specific information you need is buried within a book on a larger topic). However periodical articles are often about very specific topics. For example, our library only lists one book on the topic of "fire ants," but one of our electronic resources has over 90 periodical articles on this topic.
Periodicals are more likely to cover local and state topics.
It isn't likely that a national publisher is going to write about local topics, such as the pollution of Barton Springs, but there will be many articles in newspapers and magazines.