An online directory is a bit like a searchable, interactive Yellow Pages: visitors can browse by category or location for all sorts of businesses, services and retailers. There are several online directories, the best-known including Yell.com, Yahoo! and DMOZ.

Directory listings are valuable for a key reason: PageRank. Google's PageRank algorithm ranks pages in order of relevance, which is calculated in terms of the number of links in to the site and the quality of these links. Having a directory listing creates a high-quality incoming link from a valued third-party site.

Also, you might generate some qualified traffic from people actually browsing the directory itself. Because entries to directories are reviewed before posting, visitors to a directory can rely at least to some degree on the quality of the results they will find. Being listed in a directory can lend your site some credibility.

Directories like Yell.com and Yahoo! are paid directories, meaning that you have to pay a fee to be listed (unless your page is a non-profit site, in which case Yahoo! will list you for free). Your site will still have to be reviewed before it can be listed, even if you pay for your listing.

The Open Directory Project, otherwise known as DMOZ, is a non-profit categorised directory of websites and pages, staffed by volunteers. The name DMOZ comes from the site's Domain Names, dmoz.org, which is itself an abbreviation of directory.mozilla.org, its original address. The major benefit of DMOZ over other directories is that it is free to be listed. Another key benefit is that Google's directory is just DMOZ downloaded! So if you are listed in DMOZ, you are also listed in the Google directory, and that means not one but two major links in for your site. Not only that, but hundreds of other smaller sites download and list the directory. A listing in DMOZ can single-handedly boost a PageRank from 3 to 4 or even from 4 to 5.

I'll focus on getting listed in the DMOZ directory because much of what you need to know applies to other directories as well. If you've ever tried to get listed before, you'll know that it can take a long time. DMOZ claims to have nearly 60,000 editors, but this number is misleading – many of these editors are inactive or only slightly active. There is also a huge backlog of sites to be reviewed, because each editor has control of a particular category. Some categories will be flooded with entries every day, whilst others will only receive an entry or two a week.

But often, applicants slow down the process even further. If you submit your site to the wrong category, when it eventually gets to the front of the queue, the editor realises it's in the wrong place and sends it on to the right category. They might even send it to the *wrong* category, and the process will start again: your site will start at the back of the queue. So always choose the most specific category you can!

Some sites are rejected because one of DMOZ' policies is only to include websites which have a significant proportion of original content. Too much affiliate material on your site can lead to it being rejected. Also, if the title and description you put forward are unsuitable, this can lead to site rejection. Check out DMOZ' guidelines before you apply. You are not informed if your site has been rejected, and there's no way of finding out if it has. It's worth getting your submission right the first time, to avoid considerable delays.

Online directory listings are worth chasing. Make sure that your application follows all the necessary guidelines, and you will hopefully soon find your PageRank climbing.

By Natalie Catchpole