This plugin is written from the ground up by WordPress SEO consultant and WordPress developer Joost de Valk to improve your site's SEO on all needed aspects.
While this WordPress SEO plugin goes the extra mile to take care of all the technical optimization, more on that below, it first and foremost helps you write better content.
WordPress SEO forces you to choose a focus keyword when you are writing your articles, and then makes sure you use that focus keyword everywhere.
Write Better Content With WordPress SEO
Using the snippet preview, you can see a rendering of what your post or page will look like in the search results, whether your title is too long or too short and your meta description makes sense in the context of a search result.
This way, the plugin will help you not only increase rankings but also increase the click-through rate for organic search results.
The WordPress SEO plugins Linkdex Page Analysis checks simple things you're bound to forget. It checks if you have images in your post and whether they have an alt tag containing the focus keyword for that post.
It also checks whether your posts are long enough, if you've written a meta description and if that meta description contains your focus keyword, if you've used any subheadings within your post, etc.
The plugin also allows you to write meta titles and descriptions for all your category, tag and custom taxonomy archives, giving you the option to further optimize those pages.
Combined, this plugin makes sure that your content is the type of content search engines will love!
Technical WordPress Search Engine Optimization
While out of the box WordPress is pretty good for SEO, it needs some tweaks here and there. This WordPress SEO plugin guides you through some of the settings needed, for instance by reminding you to enable pretty permalinks.
And it also goes beyond that by automatically optimizing and inserting the meta tags and link elements that Google and other search engines like so much.
Meta And Link Elements
With the WordPress SEO plugin, you can control which pages Google shows in its search results and which pages it doesn't show. By default, it will tell search engines to index all of your pages, including category and tag archives, but only show the first pages in the search results.
It is not very useful for a user to end up on the third page of your personal category, right?
WordPress itself only shows canonical link elements on single pages, WordPress SEO makes it output canonical link elements everywhere.
Google has recently announced they would also use rel="next" and rel="prev" link elements in the head section of your paginated archives, this plugin adds those automatically, see this post for more information
WordPress SEO has the most advanced XML Sitemaps functionality in any WordPress plugin. Once you check the box, it automatically creates XML sitemaps and notifies Google and Bing of the sitemaps existence. These XML sitemaps include the images in your posts and pages too, so that your images may be found better in the search engines too.
These XML sitemaps will even work on large sites, because of how they're created, using one index sitemap that links to sub-sitemaps for each 1,000 posts. They will also work with custom post types and custom taxonomies automatically, while giving you the option to remove those from the XML sitemap should you wish to.
Because of using XSL stylesheets for these XML sitemaps, the XML sitemaps are easily readable for the human eye too, so you can spot things that shouldn't be in there.