Yoast has surpassed all other SEO plugins on the web as the best. Created and maintained by Joost de Valk, Yoast tweaks WordPress to give search engines exactly what they need to help your content rank higher.
Plugin: WordPress SEO by Yoast
WordPress Plugin Page: http://wordpress.org/extend/plugins/wordpress-seo/
Install: Through WP Dashboard or FTP
Difficulty: Very Easy (with advanced settings)
Rating: High (1,000+ Ratings)
SEO plugins assume you are familiar with how SEO works. Using the tools in this plugin will only benefit those who understand their uses. It’s encouraged to learn more about SEO in order to use this plugin more effectively.
You can now easily add meta titles and descriptions within each post, page, category, and tag. This makes it easy to keep duplicate generated content from being created. There are some other great options like the ability to remove the word, “Category” from the permalinks when using categories in the permalinks.