With the vast advancement in information and computer technology, using information contained in web pages as evidence in patent invalidation proceedings is quite common nowadays. However, since information on the internet changes more frequently than information in conventional media, it is relatively difficult to preserve web page information or to use such information as legal evidence. Hence, archived web pages that are retrievable using the Wayback Machine, a service provided by the Internet Archive, a non-profit organisation, have become an important source of prior art data in patent invalidation proceedings.