Search Engines like Google, msn etc takes a snapshot of each web page it examines and caches (stores) that version as a back-up. The cached version is what Google uses to judge if a page is a good match for your query.
An index is a system used to make finding information easier. Search Engines use this method to create a table of relevant websites onto the server to be fetched as & when required.Contact Us for more details ( contact@oxosolutions.com | further queries ).