The size of index is one of the components to make a search engine to be good. The relevancy of final items and the quality of its content are sure things that must be taken into account.

It is valid to say that for the previous three-and-a-half years ago, Yahoo's search results were licensed to pass trough Google's. In that way, Google conquered its space in the internet as the best known search-engine-site. Since their split, a rough rivalry between them takes place, since search-generating business is crucial for a successful strategy of marketing.