The persistence of memory is our umbilical cord to our past and our present. But what exactly is meant by "memory?" Memory can be defined in at least three ways: remembrance, or memory of a person or thing; memorial or record of an event; and memory as a power of the mind. The United States Holocaust Memorial Museum's primary mission is to advance and disseminate knowledge about the Holocaust; to preserve the memory of those who suffered; and to encourage its visitors to reflect upon the moral and spiritual questions raised by the events of the Holocaust as well as their own responsibilities as citizens of a democracy. In this paper, using three web exhibitions we will exemplify how these different notions of memory are addressed within the context of the Museum's mission. In the Voyage of the St. Louis (www.ushmm.org/stlouis) exhibition illustrates how the advancing and dissemination of knowledge about an event may be enhanced by not only a recitation of the history but also by transparently explaining the research process that resulted in our understanding of the history. Here memory is excavated and assembled to enhance the visitor's retention of the knowledge and understanding of the history. The Search section of the site includes an experiential component in which visitors are invited to engage in their own research, piecing together personal histories from documents and other fragments of memory. We hope that the element of memory as a power of the mind plays a role in the visitor remembering and learning through experience. In the Jewish Displaced Persons website (www.ushmm.org/dp) , the Museum employs personal remembrances in the form of oral testimonies to enhance the primary narrative of the exhibition. Statistics show that the oral testimonies are generally the first media visited and most frequently accessed. Given the important role of the oral tradition in our personal and collective memories of past events, how best can museums exploit this tradition in their on-line components. Last, in the Kristallnacht website (www.ushmm.org/kristallnacht) , we look at the Remembrances section of the site. This is a memorial space in which visitors are invited to leave remembrances. Its popularity with visitors raises the question of how to provide memorial spaces for visitor expression and social interaction online. How do visitors invest the space with their own thoughts and emotions?