Meta descriptions are an important SEO factor that can influence both page ranking and organic search visits. A meta description
is a brief statement explaining to search engines and users what your page is about. About the length of a Tweet, this 115-160 character sentence is your opportunity to creates interest in the page while being sure to use keywords that demonstrate search relevancy. Meta descriptions may not always show in search engine results though, nor will they directly affect your rankings. However, meta descriptions can indirectly affect your search engine results in a number of ways. The use of keywords in descriptions may not affect your ranking, but keyword matches are none the less bolded.
This can be compelling to a user in determining how relevant a web page may be to what they were looking for, influencing them to click or not. A high click-through rate is one of the main goals of most websites concerned with traffic and rankings, so meta descriptions should not be taken lightly because of this. Also, social networks and social bookmarking networks use meta descriptions. When posted in a status update or other, the meta description displays along with the title and associated thumbnail. A strong meta description can be a useful tool in influencing social factors such as share-ability and virality, especially if content marketing, views and readership are priorities (Kiss Metrics
). If you want to know more about the different parts of meta tags, check out my post on meta keywords