Ask any SEO expert, and you are likely to get the same response. Meta Descriptions are important to your website. However, it is the how and why that determine how much help they will actually be. On a basic level meta descriptions give an explanation of what your site, page or article is all about. On a slightly more complex level it gives search engines an opportunity to display that description to their searchers as opposed to pulling primary (or worse, random) content from your pages. Herein lies the strength and dangers of meta descriptions. They can range from very good to very bad to just plain ugly.
A good meta description is really not so much different than any good description in that it contains three key ingredients. Good meta descriptions are:
Accurate: Good meta descriptions give a true representation of what the website, page or article is all about. They do not mislead, nor do they abandon the task of giving a description at all. If the article is about why alpha consumers should be interested in branding, a good meat description might be "3 Reasons Alpha Consumers Need Better Branding."
Understandable: Good meta descriptions use terms that are understandable to both their end users and to the Search Engines that will wrangle them. This is where keywords come into play. Using our example above we see that the key words/phrases "alpha consumers" and "branding" are used. These are words that are largely understood by our target audience and often queried in search engines.
Intriguing: Good meta descriptions make you want to visit the website, page or article that has just been described. Obviously, the intrigue itself will vary as you move toward or away from you target audience; this is not only inevitable, but even good. Again referring to our example above, we see the use of intriguing words/phrases like "3 reasons", "need" and "better" as well as the use of alliteration. These small devices make our description measurably better than a description that is unreliable, confusing and boring.
Likewise a bad meta description not only fails to meet these requirements, but often runs counter to the spirit in which they are given.
Unreliable: There are times when, in hope of gaining more traffic, websites will use compelling meta descriptions that quite simply don't relate to their website, page or article. Let me go ahead and tell you: this does not work for long. A search engine can pretty quickly identify inconsistencies between content and description. Even worse are meta descriptions of the spurious nature. These descriptions intentionally lure unsuspecting viewers to see content they otherwise would not want to view.
(I.E. Claiming to have cartoons when you really have explicit content.)
Confusing: A common mistake made with meta descriptions in regard to SEO is to overuse keywords. Using our example above, it is quite appropriate to write a compelling sentence that uses applicable keywords. It is inappropriate however to list a string of keywords in hopes of appealing to a wider query base.
(I.E. "branding, logos, ads, image, visual representation, alpha consumer, wealthy, rich, affluent, disposable income, design, graphic, development, websites, top, most, biggest, important")
Boring: A clear and correct description is important, but don't forget to make it compelling. A boring meta description is a bad meta description. No, a search engine will not be more or less compelled to list your site based on how intriguing your description is. Remember, though, that a search engine will often display your description as the snippet in their listing. So, you have an opportunity to beat out your competition before your site is even visited.
(I.E. "3 Reasons Alpha Consumers Need Better Branding" might be more clickable than "The necessities and precedence of quality branding for an affluent and innovative consumer.")
What could be uglier than an unreliable, confusing and boring meta description? One that doesn't exist at all. Each website, page and article has the potential to be better optimized with the use of meta descriptions. If SEO is important to your website at all (and in a comprehensive sense, it should be) then it is worth having accurate, understandable and intriguing meta descriptions. To forgo this option is to risk indicating to search engines that optimization is not important to you. You also risk showing your potential clients spinets that do not represent in a clear, correct and compelling way what you are all about.