數位圖書館的定義很多，在二十世紀九○年代中期，數位圖書館幾乎視同電子典藏或數位典藏的同義字。從一個圖書館員的角度而言，數位圖書館的意義包括了數位典藏與睥位服務兩種圖書館的職能，缺一不可。二十一世紀網站時代的網站圖書館正是結合數位典藏與數位服務的圖書館新型態，具有虛擬館藏與實體服務的雙重功能，並且可以符合廿一世紀初葉，人們對圖書館服務的需求。
本文試就一九六○年至二○一○年間資訊傳播應用發展狀況，預測網站圖書館時代來臨；從圖書館量藏的問題提示網站圖書館內涵佈局的重要性；說明資庫與知識庫為網站圖書館的核心典藏，資料庫及知識庫也是傳統圖書書庫媒體數位化的延伸；重要的是建杜讀者網友悠遊涵域，為網路生活的人們找到一個交集中心，不僅是開放性的園地，也是教育性、知性、報導性、和娛樂性資訊的傳遞樞紐，並形成資訊活動第二階段搜尋查找的出發點；最後望網站圖書館組建成一個多度空間的圖書館服務網，發揮比以往圖書館更大的服務能量，成就更重要的社會功能。

　　　　　The definitions of digital library are various. In the last of 20 t century, digital library was almost the synonym of electronic collection and digital collection only. But from librarians' points of view, the digital library inevitable should include two kinds of library functions, the collection and the service. Website library is the new pattern of the combination of digital collection and digital service. In this new cyberspace century, it contains dual function of virtual collection and all real services including the Internet service that satisfy users' needs in the beginning of the 21st century.
The web-site library builds a new cyberspace for web browsers to communicate. It plays a disseminating center on web that provides educational, learning, reporting and entertaining information. In the future, web-site library will develop a multiple serving network to bring its high quality into full play and accomplish the important social function in the coming knowledge management ages.