The publisher can be:
Scholarly - a university, professional, or academic press; for example: Oxford University Press, American Psychological Association, Elsevier
Popular - reputable book publisher, magazine, or newspaper; blogs
Learn about publishers by visiting their websites and looking in the "About" section. You can learn more about publishers by Googling them and seeing what other sites say about them.
To find out who the publisher is, look either on the page near the front of the book that gives the title, or look on the page that has the copyright information.
You can learn basic information about a magazine, journal or newspaper by visiting that periodical's website. Look for an "About Us" section.
You can also learn more from Ulrich's Global Serials Directory (link is below). It usually provides a description, intended audience, and sometimes reviews.