Memento wants to make it as straightforward to access the Web of the past as it is to access the current Web.
If you know the URI of a Web resource, the technical framework proposed by Memento allows you to see a version of that resource as it existed at some date in the past, by entering that URI in your browser like you always do and by specifying the desired date in a browser plug-in [FireFox Plugin for time-traveling on the web].
Memento allows you to actually browse the Web of the past by selecting a date and clicking away. Whatever you land upon will be versions of Web resources as they were around the selected date. Obviously, this will only work if previous versions are available somewhere on the Web. But if they are, and if they are on servers that support the Memento framework, you will get to them.
Memento: Time Travel for the Web
This project seeks to integrate preservation capabilities into standard Web practices. The project assumes that the core technologies for creating a “preservation-ready” web are in place; what is needed is a concerted, high-profile effort to instantiate the technologies in simple protocols, methodologies and software.
This Memento experiment is supported by the Library of Congress under the National Digital Information Infrastructure and Preservation Program.