Search engine is the term with which we are accustomed with very much. But the web directory is not that same. The web directories are older than search engines according to the time of their invention. There are some similarities and some differences between search engines and web directories. Web directories were present before the invention of search engine. The popularity of web directories were also came before the search engines. Web directories are nothing but a directory form where different types of resources and information are gathered by human hand. . The resources are here various kinds of link which are arranged according to their names. It can be arranged alphabetically, name wise and differently. It is exactly like a directory setting where various collections of links to various site are collected or arranged maintaining some attributes and qualities.
Web directories offer a search but it is not like the search of a search engine. If the search directories do not offer the search facility of some kind then it would be completely impossible to browse thousands of pages for computers. But it can not be a search engine in two ways. Fundamentally most web directories are different from search engines as directories are edited by humans and URLs here are not collected by spiders but they are submitted by the site owners. The main advantage of Web directories is that no matter how clever spiders become, when there is a human to view and check the pages, there is a lesser chance that pages will be classified in the wrong categories. And the disadvantage with this difference is that the lists in web directories are sometime outdated because if there is no human being to edit and submit the directories then it will be outdated. You have to edit and check the submission unless it will be not working. But this is not that bad because search engines also deliver pages that do not exist anymore. And the other disadvantage with it is that sometimes you might have to wait half a year before being included in a search directory. Mainly these differences are occurred because it is not automatically maintained or mechanically maintained. On the other hand the search engines are automatically maintained with out any help of human hand. As in web directories there is no hand of spiders that is why anyone should go there and submit the URLs to the search directories.
The job of search engines is much easy and automatic but the job of web directories is not automatic but manually done. Once you are included in a particular directory, in most cases you can stay there as long as you wish to and wait for people and search engines to find you. The fact that a link to your site appears in a respectable Web directory is good because first, it is a backlink and second, you increase your visibility for spiders, which in turn raises your chance to be indexed by them.