「最小努力原則」假定，人會採取可能耗費最少勞動的行為，來完成特定任務：即，將必要之努力最小化。
And yet what is this Principle? In simple terms, the Principle of Least Effort means, for example, that a person in solving his immediate problems will view these against the background of his probable future problems, as estimated by himself. Moreover he will strive to solve his problems in such a way as to minimize the total work that he must expend in solving both his immediate problems and his probable future problems. That in turn means that the person will strive to minimize the probable average rate of his workexpenditure (over time). And in so doing he will be minimizing his effort, by our definition of effort. Least effort, therefore, is a variant of least work. (Zipf, 1949) ¹⁾
The PLE's premise is that, in performing tasks (e.g., writing or speaking) individuals adopt a course of action that will expend the probable least average of their work-the least effort. (Case, 2005)²⁾

例如，在可接受的品質水準下，人們傾向選擇既有的資訊來源，而避免花費力氣去尋找、評估更好的新資訊來源。

• 1935年，哈佛大學的語言學家齊夫(George K. Zipf)提出的詞彙使用理論Zipf's law, 齊夫定律）。其一是單詞的音素越少，被使用的頻率越高；其二是頻率分布理論（Zipf Distribution, 齊夫分佈）：在人類的自然語言運用中，一個單詞的出現頻率與其在頻率表裡的排名成反比。即，排名第一的單詞出現的頻率，是第二名單詞的兩倍；而第二名單詞出現的頻率會是第四名單詞的兩倍。《語言的精神生物學(The psycho-biology of language)》³⁾
• 1949年，齊夫根據其語言學的發現，推論出人類具有選擇耗費最小工作而達成最大效益的傾向。《人類行為與最小努力原則：人類生態學導論(Human behavior and the principle of least effort: An introduction to human ecology)》⁴⁾。

最小努力原則往往與決策行為理論的成本效益典範（cost-benefit paradigm）被視為是相同的概念，但兩者並不盡相同。最小努力原則並未考量人們會全然理性的評估並優化其決策結果。相反地，最小努力原則主張只要能最小化其努力，人們會接受其工作結果擁有更低的品質或更少的數量。

最小努力原則除了原本應用在原本語言學上的研究之外，圖書資訊科學也廣泛地應用最小努力原則於服務規劃，資訊系統設計與書目研究上。並且在科學研究上作為對人類資訊行為的理解與解釋理論來源，例如參考資源的使用行為研究，以及資訊檢索行為研究等。

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