Principle of least effort  The principle of least effort is a broad theory that covers diverse fields from evolutionary biology to webpage design. It postulates that animals, people, and even well-designed machines will naturally choose the path of least resistance or "effort". It is closely related to many other similar principles: see Principle of least action or other articles listed below. This is perhaps best known or at least documented among researchers in the field of library and information science. Their principle states that an information-seeking client will tend to use the most convenient search method in the least exacting mode available. Information-seeking behavior stops as soon as minimally acceptable results are found. This theory holds true regardless of the user's proficiency as a searcher, or their level of subject expertise. Also, this theory takes into account the user’s previous information-seeking experience. The user will use the tools that are most familiar and easy to use that find results. The principle of least effort is known as a “deterministic description of human behavior”. The principle of least effort applies not only in the library context, but also to any information-seeking activity. For example, one might consult a generalist co-worker down the hall rather than a specialist in another building, so long as the generalist's answers were within the threshold of acceptability. The principle of least effort is analogous to the path of least resistance. The principle was discovered by the Italian philosopher Guillaume Ferrero, who published it for the first time in an article in the "Revue philosophique de la France et de l'étranger", 1 January 1894. About 50 years later this principle was studied by linguist George Kingsley Zipf who wrote "Human Behaviour and the Principle of Least Effort: An Introduction to Human Ecology", first published in 1949. He theorised that the distribution of word use was due to tendency to communicate efficiently with least effort and this theory is known as Zipf's Law. Within the context of information seeking, the principle of least effort was studied by Herbert Poole who wrote "Theories of the Middle Range" in 1985. Librarian Thomas Mann lists the principle of least effort as one of several principles guiding information seeking behavior in his 1987 book, "A Guide to Library Research Methods". Likewise, one of the most common measures of information seeking behavior, library circulation statistics, also follows the 80-20 rule. This suggests that information seeking behavior is a manifestation not of a normal distribution curve, but a power law curve.