Format is the way tangible knowledge is disseminated. The essential characteristic of format is the underlying process of information creation, production, and dissemination, rather than how the content is delivered or experienced.
Learners recognize that there is a process behind the production of each resource. Knowing how information is created and produced for specific formats helps learners to evaluate the quality of a resource and illuminates benefits (e.g. the review process for an article) & constraints (the lack of currency of a book) of those resources.
Think about where you get information relevant to your daily life.
Are there some news media outlets that you automatically trust? Are there some sources that you always doubt / never believe?
When a celebrity tweets about a topic important to you, do you wonder if they are getting paid to promote some content? How believable are they on that topic? Why? Will reading this tweet persuade you to change how you think about the topic?