What are stop words and how do they effect your search?
Search engines for the most part do not acknowledge and or record what are commonly used words in order to filter and to speed up searches. These are known as "stop words." A search engine might replace it with some sort of indicator to ignore the word. The sentence may retains most of its relevancy. Some search engines store every single word on a web page but they don't search for certain ones to save time. Many of the older search engines would get bogged down with these common words having to search millions upon millions of them before they could move on to the next word in a sentence. Now they may simply filter them out as seemingly insignificant.
Chances are unless you are doing an advanced search you won't need them either. Just looking for two or three words as a key phrase or long-tail is enough to find relevant pages.