Google Explains The NOINDEX, NOFOLLOW, NOARCHIVE & NOSNIPPET META Tags

The Google Blog has a basic but clear explanation of the robots exclusion protocol.
In this Post, Google explained how the NOINDEX, NOFOLLOW, NOARCHIVE and NOSNIPPET META tags function.

In Short:

• NOINDEX tag tells Google not to index a specific page
• NOFOLLOW tag tells Google not to follow the links on a specific page
• NOARCHIVE tag tells Google not to store a cached copy of your page
• NOSNIPPET tag tells Google not to show a snippet (description) under your Google listing, it will also not show a cached link in the search results