Before you step into the fraternity of SEO you must clearly understand few important terms related to SEO. One of the most important terminologies is search engine and search directories. Both of these help you find websites and required URLs but there is a great difference between these significant words of SEO.
Search engines are the big daddies for which the whole SEO services are conducted. These are the portals which gives you results for your searches. You can find URLs related to your desired information in these search engines. The major search engines are Google, Yahoo, MSN, AltaVista etc. These search engines help you reach your target audience. Search engines work on keywords. When any users look for your keywords in these search engines, the engines direct users to sites with similar keywords. Search engines don't have any category specific page. You can type any word, letter, sentence in these search pages. Search engines have spiders or crawlers who everyday crawl the web to find Meta tags for different searches. These search engines have a huge database where all the websites are indexed.
Search directories are online resources for searches and online marketing. These directories also have a huge database but they provide several different services than search engines that provide only search results. Following are few important points about search directories.