Many people have written asking about search engines - how to use them, where to find them and which are the best ones.

Basically, a search engine is an Internet programme which allows users to search for sites or pages based on particular words. A search engine principally gathers information on sites through what are known as meta tags, keywords contained in HTML coding on a site's homepage which allow it to identify and log content.

Commercial websites register with search engines so that inputting certain words will lead to a suggested link to their site. In the case of The Irish Times website, www.ireland.com, the keywords include the names of Irish politicians and tribunals of inquiry. Search engines also gather information on non-commercial sites and amateur sites.

Meta tags greatly aid in driving traffic. Because of this, they are prone to being misused.

This misuse is known as spamdexing. An example of how it works, from my own experience, would be something that happened a year ago when I was researching a story on the millennium.

Putting the word millennium into a search engine led to suggestions of links to scores of pornography sites, whose only connection to the millennium celebrations was that they had used that word as a meta tag.

So, aware of the dangers of misuse, let's take a look at some of the engines.

Yahoo (www.yahoo.co.uk) is one of the best-known and best engines. Its main advantage at this address (it has different addresses for the various parts of the world it services) is that it concentrates on Irish and British information. You can choose to search all of Yahoo, Ireland only or the UK only.

It has a very text-heavy homepage that breaks the searches down into useful categories such as education, government, health, and news and media. The search is very comprehensive and fast. Using "Irish Universities" as a sample search leads to a page-and-a-half of links. A very useful engine. Doras (www.doras.ie), which was set up four years ago, claims to be the world's largest and most comprehensive directory of Irish and Irish-related websites. It features 14 categories, including arts and culture, property, recruitment and travel, and more than 500 sub-level categories.

More than 10,000 sites are available through Doras, either by browsing or searching. All sites of Irish interest get a 70word review and a shamrock rating from 1 to 5. The search is fast, but, using the same sample search, "Irish Universities", leads to just four links.

Altavista (www.altavista.com) claims the title of "premier knowledge resource on the Internet". It also aims to provide immediate access to "the richest, most relevant information". Operating from Palo Alto in California's Silicon Valley does not prevent it finding 200 links to the sample search, though what the homepage of the Dutch Dart Catamaran Association has to do with "Irish Universities" I'm not sure. One of the best resources of Altavista is that it can search for sites in 25 different languages, from Chinese to Lithuanian to Swedish. This is certainly a boon to anyone studying languages. Specific areas of the site such as entertainment, news, sports and health also attract a lot of traffic. A very fast and well-organised search engine.

All the Web (www.alltheweb.com) is not one of the more well-known search engines, but it has a refreshing view of the Internet. Aiming to be "All the Web, All the Time", it works on the premise that more than half of the estimated 800 million pages on the web are duplicates. The theory is that being aware of this helps them attain more accurate information.

Using the same control search as with the others, proves that All the Web is certainly very fast, but the information found is very similar to that obtained through Altavista. If you had to choose between the two, Altavista is more attractive due to its additional features. That said, the MP3 music search from ATW's homepage will be the reason many people go there.

Web World will look at other search engines in a later column.