According to the University of Maryland Libraries,
Traditionally, students setting out to write research papers could trust that the library materials they use are not unduly biased. An academic library's print, nonprint and electronic resources have been edited and checked for accuracy by scholarly organizations and publishers, then carefully evaluated by professional librarians for inclusion into the library's collection.
The information found on the World Wide Web has added a new dimension to selecting resources. Anyone can create a Web site. No one has evaluated the quality or accuracy of the information found on the Web before you come across it. Some Web sites are created by subject experts .... However, the vast majority of Web sites are created by non-experts.
The information timeline can help you determine which types of sources to look for based on the type and depth of information you need: Once you know which type of sources you want to look for, you can more efficiently decide where you need to look.
As an event develops, information about it is generated and disseminated. The first reports show up on the Internet, television, and radio. First reports usually focus on the quick facts: who, what, where. As time passes, information filters through different types of resources, with the level of coverage increasing and becoming much more detailed and analytical.