Directory Submission is a method to get top ranking in search results. It creates permanent backlinks in form of listing to the site with other details so you can get better Page rank in free. Unlike other SEO (search engine optimization) tactics, directory submission has long time benefits to get better backlinks from high PR web pages.
Moreover directory submission is easy, free, time saving and improves site through helping search engines to index a website in suitable niche category. Therefore directory submission is an important task into SEO link building practices. The most important thing is it provides guaranteed better indexing in search results if done in proper way.