Worlds Biggest Directory
It is difficult to state what the world’s biggest directory or index is. When it comes to Web directories, one of the leading candidates is the DMOZ website. It has 4,814,779 sites in 1,004,396 categories. But giving exact figures is difficult. The nature of the subject means it is always being updated.
Definitions and Concepts 
Before size can be determined, definition is necessary. The traditional directories are big books with an alphabetical list of addresses and names. The book can also contain lists of different establishments and their contact numbers. The term is also applicable to a tablet or board that contains the floor numbers.
Computer Directories
In computer terminology, the directories or folders contain the files in the computer. These folders are arranged hierarchically and may contain subdirectories. The size of the directories will vary. In Windows PCs, the OS folder is probably the biggest.
The folder size could run into the hundreds of megabytes or gigabytes depending on the installation done. The complexities involve in definition is the reason why determining the world’s biggest directory is hard.
Web Directories
These are websites that that provide access to websites. These sites are listed in categories. You can search or browse through the list. One of the fine instances of this would be the Open Directory Project. This is also used in network information services. One of the best known examples is the Domain Name System (DNS). DNS is a hierarchical index service. Its lookup function is simple.
By contrast, distributed hierarchical object-oriented directory technologies have more powerful search and browse features. These are utilized for public key infrastructure, network information services and white pages. Good examples are LDAP and X.500.
Web Directories and Search Engines
The two are not the same, although some search engines have them. Unlike search engines, pages are not shown based on keywords used in the search. Rather, the sites are classified by categories. It should be noted that the entries there are found by people, not web crawlers.
Often, the website will allow webmasters to submit their site. Editors will review the site before it is accepted. These should not be confused with RSS feeds. They are similar, but RSS contains RSS feeds and not links.
As these facts show, trying to determine the world’s biggest directory can be difficult. Aside from the intricacies involving definition, there is also the fact that these are always changing and growing. It makes number tracking difficult.
