There is an ongoing debate as to whether search engines use keywords in meta descriptions to rank a web page. One thing is certain though, Google sometimes (but not always) uses the description as a snippet when it presents search results to a user on the Search Engine Results Page (SERP). Generally if the user is searching for a URL this is the case.
The main point here is that you are in control of what your meta description states and a well crafted statement about the page can increase your clickthrough rate.
When writing the description it is helpful to think in terms of advertising. What is the user looking for and what will compel him or her to choose your site over the numerous others that will be displayed? A short and snappy summary of the page with your prominent keywords (they will be in bold text) near the beginning of the description will catch a users eye.
The description should be no longer than 155 characters or you stand the chance of having the message truncated. The meta description allows you to provide the search engine with a meaningful description of your page when they are unable to automatically create one from the page content.
Meta descriptions are often used when the search engine displays extended site links. It is very important therefore to write a separate and distinct meta description for each and every page on your website. Extended site links are highly keyword dependent, so to benefit most from your meta descriptions your site must have a uniform purpose and your keywords must reflect this purpose. The use of these keywords at the beginning of your meta description will increase the odds that the search engine will use the meta description as a snippet.
Meta descriptions are especially important in social media marketing such as Facebook and Google+. If there is no meta description the search engine will usually default to the first sentence used in the article and this will not properly convey what the whole article is about. The majority of marketers on social networks overlook this fact and by creating the meta description you will enjoy a competitive advantage over your competition.
A meta description in general is one of several meta elements that provide search engines with information that helps the algorithm index and categorize the page. They are not visible to the user as they are part of the HTML document. In the 1990′s they were essential to search engines in ranking a page but as webmasters learned ways to gain an advantage through keyword stuffing and other black hat SEO techniques search engines gradually started looking to other criterion in search technology.
Today meta elements have a far less effect on determining ranking of any given page as search engine robots have become more refined in sniffing out spamdexing and keyword stuffing.
The search engines of today use a variety of criterion to establish page rank such as:
The search algorithms of today are constantly changing and evolving but this does not mean you should disregard older aspects of page development. At the very least a well written meta description will be a sign of quality and technical precision in the eyes of search providers. These two criteria do play a part in ranking and will set you apart from those who are looking for the fast track to the top.