What is Advertorial?

Legal Definition
An advertorial is an advertisement in the form of editorial content. The term "advertorial" is a blend (see portmanteau) of the words "advertisement" and "editorial." Merriam-Webster dates the origin of the word to 1946.

In printed publications, the advertisement is usually written in the form of an objective article and designed to ostensibly look like a legitimate and independent news story. In television, the advertisement is similar to a short infomercial presentation of products or services. These can either be in the form of a television commercial or as a segment on a talk show or variety show. In radio, these can take the form of a radio commercial or a discussion between the announcer and representative. The concept of internet-based advertorials is linked to native advertising; however, whether the two terms are synonymous is a point of discussion.
-- Wikipedia
Legal Definition
An editorial style ad that is made to reach more customers. The TV version of this is an infomercial.