SEO Siloing WordPress plugin allows bloggers to configure blogs that follow the “SEO siloing” technique where posts are grouped by category and cross-category links are only made to special category landing pages.
You would normally only use this plugin if you have defined the permalink structure for your blog to include the category name. In other words, all your postings use the form /%category%/%postname%/ for their permalinks. This isn't a requirement, though, but it's a recommendation. You can actually use the plugin on any page or post, but if you use it on a non-page you have to explicitly give it a category to display.