Was there any life before Google? Were the users searching and browsing the Internet, just like they're doing it today? Of course; obviously not at the same level, but browsing and searching were natural actions even from the very first days of what we call the world wide web.
15-20 years ago, people used to list their websites into link directories - practice still done today, but with other purposes - as they were one of the main traffic sources back then. Sure, there were engines like AltaVista (owned by Yahoo, but no longer available), Yahoo, Lycos.com, Go.com and some other search engines, but their popularity was not extremely high.
Nowadays, people still submit their websites into link directories, mainly in order to promote their business, but also for search engine optimization purposes. The main advantage offered the by the link directories is the fact that they allow users to place a dofollow link - a link that does not have the attribute nofollow, and therefore, increases the authority of that site - and get some targeted anchor texts as well.
There are many types of link directories:
- free submission: anybody is allowed to place a link to their websites, as long as they respect the guidelines.
- Article directories: usually, they require unique articles in which the submitters are allowed to place a link or two as long as the articles are unique and without errors;
- Premium: usually, people call a premium directory a high quality directory that has a high page rank, has never suffered a major penalty and which has a very strict policy related to the listed websites. Usually, most of these premium websites require an annual fee in exchange of an extremely powerful link.
The major problem with most of the web directories is the fact that they are often spammed to death by robots designed to submit automatically websites. And since the robots tend to submit the same descriptions, titles and meta tags in thousands and thousands of directories, Google - as well as all the other search engines - tends to retrograde them and decrease the value of their listings as well. This is why, a link building campaign must be always based only on high quality resources such as Ezinearticles, GoArticles and any other high quality link directory - link or article based - and not just on spammy-second-hand directories that are already full with shady links.