As a search engine prowls your site, it gathers information from the title, headings, content, and Meta Tags such as description or keywords. It compares the words within each of these sections and "ranks" the site dependent upon how well the information matches.It is important to understand that a default installation of WordPress does not contain the description and keywords meta tag data. Meta tags can be added manually, through changes to the Theme template files or through WordPress Plugins.
A good question to ask is if meta tags are still necessary. They used to be more helpful, providing important information to the Internet browser. As browsers became more sophisticated, they stopped needing a lot of hand holding in order to figure out if your site is in English or Chinese.
Some search engines don't use the meta tag information any more because many people abused it. In fact, meta tags may not represent the content of your site. But, it still doesn't hurt your status with search engines if you make use of these little bits of information, and do so truthfully.
Without a doubt, content is the biggest contributor to search engine page ranking, so if you want to raise your rankings, make sure you have quality content.
Keywords meta tags, on the other hand, are still used by Google and other important search engines to categorize and rank your website. Those engines compare the keywords with the content, giving you "points" for having your keywords match your content. Keywords are one of the most important meta tags you can add to your WordPress site.
Covering all the reasons meta tags are and aren't important to search engines is beyond the scope of this article.