Once any web page or a website is published on the Internet, cached copies of those exist at different locations. Also, search engines cache copies (snapshots) of these at regular intervals.
So, to view any web page that is currently offline/deleted or has changed, these cached versions can be of big help. Based on this, Mozilla Firefox has a cool add-on : Resurrect Pages.
Download it from here. Once downloaded and installed, to view cached copies or previous versions of any web page, simply right click on the web page and choose “Resurrect this page”. [This works even when a webpage currently shows as offline or unavailable, simply choose “Resurrect this page” in this case too to look at cached versions.]
This will bring up a list of websites which keep the cached versions of web pages.
It includes search engines like Google, Bing, Yahoo and also archive sites like The Internet Archive.
Simply choose to open these cached versions either in a new tab, new window or in existing one and select the source.