Stop words are common words that are sometimes ignored by Search Engines when doing searches. For instance, the word “for†is ignored by Google® when doing a search, but is not ignored by Yahoo®. Each Search Engine has a different set of stop words. It is good to remember this when choosing keywords for your web pages.
The reason Search Engines have words that they ignore (stop words) is because it saves space on the Search Engine’s servers and it makes searches run faster.
