Meta Description Tags
Meta data is "data about data," and a meta description tag provides a description of the data (text, photos, graphics, etc.) found on a particular web page. Meta tags aren't visible on a web page, but instead appear in Search Engine Results Pages (SERPs), in Facebook links to the described page, etc. Their direct effect on a page showing up in a SERP is minimal these days; the main value of a good description tag is ensuring that a visitor with an interest in what appears on the page clicks through to that page. A page with a high click-through rate in SERPs is rewarded (or at least not penalized) and drawing highly-interested visitors improves Bounce Rate, which does have a direct effect on SEO.
Good description tags should be 155 characters in length (Facebook has recently forced updates to its Pages to include a 155-character limit in the About section, so this is a good clue). Another clue is Googling "texas 1st congressional district representative" and seeing that the wrhammons.com description leaves just about enough space in the Google SERP for 155 characters.