Internet上多元的搜尋系是目前網路上最常被利用的服務之一，由於網路上的資源包羅萬象、類型繁多、又隨時變動，若不能好好利用這類系統，尋找資源將有如大撈針般的困難。但隨著Internet的成長，這些資源搜尋系統也急速增加，了解這些系統的設計架構、種類特色、和未來發展，並從中選擇最適當的系統來協助檢索，已變得相當重要。同時對於圖書資訊人員而言，除了熟悉這些系統的運用外，也應開始思考資源搜尋系統在圖書資訊服務的可能應用及影響，以因應未來電子化圖書館的發展趨勢。

　　　　　One of the most popular services available on the Internet is the varous serch tools. With the rapid growth and the diversity of network resources, search tools have proved to be most helpful in finding out relevant information. The purpose of this paper is threefold. First, it introduces the development of network information retrieval and discusses the structural design of a typical search engine. It then reviews all types of search tools by cross comparing their generic features, such as content and search capability. Finally it explores the information service issues that arise from the nature of search tools.