Trade publications are commercial publications which contain discussion of current events, products, or news related to a specific industry or profession. They often use specialized terminology related to the field, and assume their audience of practitioners, professionals, and enthusiasts have a baseline understanding of that field. The authors are often practitioners in the field, industry professionals, or journalists with subject expertise and may included references or short bibliographies (but don't always). Because it is commercial it will have advertisements specific to that field. These publications are particularly important in the arts, as they will include contemporary conversations, current events, and active artists in a way that peer-reviewed scholarship cannot. Examples of trade publications in the arts include ARTnews, Art in America, Juxtapoz, Architectural Digest, Eye, etc.
The images above are of the same article online (left) and in print (right). No matter how it is published, trade publications have identifiable features that distinguish them from scholarly resources.