There are many different types of directories within the world, but the most popular in recent years has to be the web directory, otherwise known as a link directory. A web directory is a directory based entirely on the World Wide Web. It mainly specialises in linking to other websites and categorizing said links.

A web directory is not actually a search engine, as it does not display lists of web pages based on key word ranking. Instead it lists websites by a category and subcategory, for example, Article Alley is a web directory, so you will often find most directories set out in the same manner. The categories themselves are usually based on the whole website, as opposed to just one page or set of keywords, and sites are often limited to inclusion in only a few categories. Web directories will often allow site owners to directly submit their site or articles for inclusion, and will have editors (manual or automatic) who review all submissions to check whether content is appropriate and meets their specific guidelines.

Web Crawlers

Most web directory entries are also not found by web crawlers, but by humans, a web crawler is a computer program that browses the World Wide Web in a methodical, automated manner. This process is called Web crawling or ‘spidering’. Many sites, in particular search engines, tend to use ‘spidering’ as a means of providing up-to-date data for users. Web crawlers are mainly used to create a copy of all the visited pages for later processing by a search engine that will index the downloaded pages to provide fast searches.

Listings Scope

Most directories on the internet today are quite general in scope, and tend to list websites across a wide range of categories, regions and languages. In recent years, however, there have been a growing number of niche directories appearing all over the internet, these niches directories often focus on more restricted regions, single languages, or even specialist sectors. One specific type of niche directory that has a particularly large number of sites in existence is the shopping directory, which specializes mainly in the listing of retail e-commerce sites. Well known web directories include Yahoo! Directory, and the Open Directory Project, or ODP. The ODP is significant in the world of web directories because it features an extensive categorization system, a very large number of listings, as well as, of course, it’s free availability for use by other directories and search engines.

Directory Development

Over the years there have been many different attempts to make directory development easier for everybody; different features have been introduced in order to do this such as automated submission of related links by script, or any number of available PHP portals and programs. Some of the more commonly found features in directory listings nowadays include:

* Free Submission – meaning you do not have to pay to submit your content or listing

* Reciprocal links – allowing links back to the directory itself, often required in order to be listed

* Paid submission – a one-time or recurring fee for reviewing/listing the submitted link

* No follow – an attribute associated with the link submitted, meaning search engines will give no weight to it.

* Featured listings – where a link is given a premium position within a category or section, for example, the homepage.

* Bid for position – where sites are ordered based on bids

* Affiliate links – where the directory earns commission for referred customers from the listed websites.

Human edited directories

A human edited directory is created and maintained by editors who add links based on the policies and guidelines particular to the directory in questions. Human-edited directories are often targeted by SEOs (or Search Engine Optimizers) on the basis that links from reputable sources will improve rankings in the major search engines. Some directories may prevent search engines from rating a displayed link by using redirects, nofollow attributes, or other techniques. There are many human-edited directories, including the Open Directory Project and of course, Article Alley. Many directories are edited by volunteers, who are often experts in the particular category in question. However, these types of directories can often come under criticism due to the long delays it may take before a submission is approved, or sometimes for having rigid organizational structures.

In response to these criticisms, some editors have adopted wiki technology in order to allow a broader community participation in editing the directory; however this comes with the risk of introducing lower quality, less objective entries. Today submission of websites to web directories is considered as a common SEO (search engine optimization) technique to get vital back-links for the submitted web site. One distinctive feature of ‘directory submission’ is that it cannot be fully automated like search engine submissions. Manual directory submission is a tedious and time consuming job and is often outsourced by the webmasters.

Article directories

Article directories are a form of Search Engine Optimization where companies and professional writers submit their articles based on a specific niche or subject. Article directories are also called Ezines or Online Magazines for the depository methods hosting hundreds or thousands of documents related to a given subject. Article directories use the technology employed by web crawlers in order to allow website owners to link back to their site using keyword articles that trigger search engines to rank pages higher. The standards required for these articles are developed by SEO experts, they tend to be of a word count between 500-800 words, with a keyword density of approximately 2-3%. While article submission sites allow link backs for SEO, they have limits to how many are normally allowed. Link backs should be keyword optimized using HREF tags with keywords in the title tag. Writing standards also prohibit keyword stuffing, so articles are reader friendly for humans and not just crawlers.