Index

An index on a computer is no different than any other index, such as a card catalog at your library; it provides a method to quickly find what you're looking for. For instance, if you created a menu of links to all of your pages, that is an example of the most basic form of index: the user gets a compact summary of what's available and can go directly to an item of interest.

A searchable index is a more complex form of index used when the amount of information is too vast to be summarized by a simple menu. A searchable index allows the user to specify explicitly what they're looking for and the search facility "automagically" returns a dynamically generated list of all available resources matching the user's request (the closest analogy in the library metaphor would be the helpful librarian).

How does the computer accomplish the search? One way would be to scan through the entire information base and check every resource for a match; unfortunately, the amount of information we commonly want to search and the speed of current computer technology would make an exhaustive search too costly in time and computing resources (it would be like expecting the librarian to read through every book in the library to find all those of interest to you).

Rather, the librarian will probably consult the card catalog (or more likely, these days, a computerized database) to more directly find the books matching your area of interest. In the same way, a server can not afford the time and resources to search every one of your web pages looking for matches to a search request. Instead, it consults a pre-prepared cross-index of each of the files (the digital equivalent of a card catalog) to quickly find a list of relevant resources directly.

So there are really two slightly different meanings to the word index in the context of computerized information. A computer index is:

• A service provided to users to rapidly locate items of particular interest to them from large stores of information.
• The internal, pre-prepared structure used by the computer system to make this rapid search possible.

On the World Wide Web, there are essentially two types of index services: those that allow you to search for web sites throughout the web (such as the ALIWEB service), and those that allow you to search at a site (such as the searchable index of WebCom Help pages).

If you're interested in getting your web site listed in the first type of web index, you'll want to read our guide to widely publicizing your web site. If you interested in creating the latter type (a searchable index of your Web site) for your WebCom site, you'll be interested in the WebCom Glimpse Indexing Facility.