Information which is organized in such a fashion that it bears directly on a specific question asked or on a specific problem for which a solution is sought, in contrast with subject-oriented information which is typically oriented around a field or branch of knowledge. A dictionary and a telephone book provide problem-oriented information, answers to the specific question what “does this word mean?” and “what is John Doe’s phone number?” A more complex example of problem-oriented information is found in a” how to” book. A standard textbook or a descriptive book provide subject-oriented information, such as “all about physics” or “all about Hawaii.” A chief distinction between the two classes of information is that a problem-oriented source will draw from as many sources or fields of knowledge as necessary to deal with the problem, while a subject-oriented source deals, in the main, with a single discipline. A strong movement toward providing information in the problem-oriented mode has come with the computer, which brings a number of attributes: virtually unlimited memory, high-speed access to information, hypertext linkage, multimedia (sound and visual images, both still and in motion), and interactivity. One of the best examples of a problem-oriented information source is found in medicine in Problem Knowledge Couplers.