I'm afraid all the previous answers are wrong! The chain of events of how a snippet is displayed in a search result is as follows:
- If you have a valid tag and it matches the content of the page, it will display this. Meta description tags are not useless as people have posted below - only meta keyword tags are.
- If you don't have a valid meta description tag but you DO have a listing in the Open Directory project (DMOZ) associated with the URL, it may display the description from this as the tag.
- If you don't have a valid meta description tag OR have a listing in the Open Directory project (DMOZ) associated with the URL, but you DO have one in the Yahoo Directory, it may display the description from this as the snippet.
- If you don't have any of the above, G will try and generate a snippet from the on-page content using analysis of the most likely useful content.
- If it deems ALL of the above to be irrelevant (very rare) it may list menu items. This is a sign of very poor site quality.
The example given page (http://cheerleaders.union.rpi.edu/) has a snippet of
Includes an introduction to current and past squads, pictures, a roster, related links, and upcoming events.
Following step 2, this page does NOT have a meta description tag but IS is listed in the Open Directory Project at http://www.dmoz.org/Sports/Cheerleading/College_and_University/NCAA_Division_III/. You will see exactly this snippet listed for RPI.
To override this behaviour, you would write your own meta description and put the following meta tag in the head of the page:
<meta name=”robots” content=”NOODP,NOYDIR” />
which is officially supported by Google:
It doesn't have anything to do with:
- rich snippets.
- meta property tags.
- tags being over 200 characters long (the limit is 160, and they just concatenate anyway.)