What is the definition for publish?

One definition is:

: to present a finished piece of work to the public

How is the process of publishing printed material (newspapers, magazines, books) different from publishing on the Internet?

Although many websites are written by people with expertise on a particular topic, this isn't always the case throughout the Internet. Sometimes people who create or post on blogs do not have a background in the subject matter, and there is no editor to hold them to a high standard. By contrast, most respected book publishers and newspaper editors look for authors who know a lot about their subjects. They also have skilled editors and fact checkers who review the information in these publications for mistakes.

What is the definition of trustworthy?

One definition is:

: accurate and dependable

People who create or post on blogs and other websites are not necessarily experts in the subject. Their “facts” may not be true. They often don’t fix errors when some are found. They may pretend that their opinions are facts. They may even choose to include unkind or harmful statements.