Use Categories for META Keywords
In addition to the keywords that you set, you have the opportunity to append the categories a single post is in. Presumably, if you use categories for your blog post (as opposed to as a structural element that many people have begun to use), these keywords can be appended into the meta keywords field as well. This can help further define the context and relevancy to the search engines.
Dynamically Generate Keywords for Posts Page
In most cases, the Dynamically Generate Keywords for Posts Page option is not required. For some setups, however, the normal flow of posts is on a separate page. This is often the case when a WordPress install is used as a content management system and the bulk of the layout more closely resembles a traditional site. The “blog” is often designated to a separate area of the site and uses a custom page template. For situations like this, the All in One SEO plugin provides the opportunity to dynamically populate the meta keywords tag on this page with the keywords you have chosen.
The All in One SEO plugin also provides three options for eliminating certain pages from being indexed by the search engine. These options are useful in avoiding duplicate content penalties but can also be overkill. Therefore, it is completely optional to designate archives, tag archives, and category archives as “noindex” links. When the search engine spiders encounter these links, the content behind them will not be indexed.
You have the option of having the All in One SEO plugin automatically generate meta description tags for all non-home pages. Usually, these meta description tags are generated with the post excerpt, something the author can predefine or WordPress can automatically generate. In the event that the plugin cannot find an excerpt, selecting this option enables it to automatically create a description that fits the blog post.