The Libraries, on the other hand, contain materials going back to antiquity and a large number that were published throughout the 19th and 20th centuries. The Web is an undifferentiated mass of documents and information. Many Web sites are self-published by individuals who are not experts or authorities on the topic. That's why the UM Libraries have an organized collection of materials selected by librarians who understand the needs and standards of the scholarly community. The emphasis in most of the Libraries' collections is material that provides an intellectual context for current information.
Many Web sites are merely commercial advertising for products and services.
Others are designed to be entertaining. They may be useful for some information needs but probably not for course work. The authors of some Web sites have strong biases that may not be based on research or informed opinion. Care must be taken to judge whether the biases are so strong as to negate the truth or value of the information presented. A weakness of the World Wide Web is that much of the information presented is shallow, incomplete, or simply redundant with other Web sites.