When anyone logs on to the Internet and wishes to find any kind of information, they always head to either a search engine or a directory. Many people think they are the same thing, but there are some major differences. Let's explore what's makes a directory different from a search engine and find out how each one works.

Search Engines

A search engine is basically a website where you can type in a word or phrase about whatever it is you're looking for. A great example of a true search engine is Google. On their main page, it's very simple, they have a one field form where you type in your query and click a button to tell Google to search its database for results that include this word or phrase. Google will come back with a page that lists the top 10 websites for that particular query. Google ranks sites in their results according to many different factors, including how many times a word or phrase appears in the text of the page, how many sites link to it, how many times keywords are included in the site's code and many, many other factors, some of which only Google knows. Other true search engines behave in a similar fashion to Google but they may rank sites using different factors than Google.

A true search engine works by sending out a spider or crawler, which is a program or script that browses around the web by following links and then saves the websites they find into their database. This is called indexing. The spiders or crawlers will build their database this way. Once a website is indexed by a search engine spider, the search engine may revisit the site later on to keep its database up to date. Some search engines send out spiders to index sites daily, even many times a day if they detect a website to be often updated. This is how they keep the search engine results fresh for searchers.

Google is a great example of a general search engine, but there are also many other search engines that are for finding other files or information on the web. You'll find search engines for images, music, files and also many search engines for different types of websites, like blogs, business sites, shopping sites etc.

Some other examples of true search engines are Altavista, Yahoo and Lycos, but there are thousands of others. For whatever you are searching for on the web, there is bound to be an appropriate search engine.

Directories

Directories are very different from search engines. They don't have programs that spider or crawl the web automatically and then index the information to make their search results. A directory is almost always human edited. Which means an editor of a directory will either accept submissions and then review and approve those sites in to their directory or they will go out and manually find sites to add to their directory. There are massive directories and also many smaller directories and niche directories. A good example of a big directory is one of the oldest sites on the web, Dmoz.org. It's a non-profit, completely volunteer edited directory. There are also many smaller directories that specialize in sites from only a certain topical area, such as fishing, pets, science, shopping, real estate, gambling, health, photography, travel... basically, you name it, there is a directory for it. There are also specialty directories for just about every state, country and region.

Search Engine Vs. Directory

A human edited directory tends to have higher quality sites in it, since the websites included have to be manually reviewed and approved instead of just crawled by a spider. Also, a directory will have clear cut categories where you can drill down to find a list of sites on a certain very specific topic. This is something that a search engine lacks. However, a search engine will have many, many more sites to offer you, and possibly much fresher results. A search engine, like Google, has a database estimated to be in the billions of pages, where even the largest directory may not even have 1 million sites or even 100,000 sites.

What's better? It depends on your needs and what you're searching for. Search engines and directories are free to use, so why not use both?