There are two ways to establish a high rankin
key word that the advertiser specified ,those search engine results can be paid per-click.
The other one is SEO(Search Engine Optimization)the services of Yahoo, Google,etc that improves the volume and quality of traffic to a site via natural search results.
Users can get a detailed information of your site by typing a key word via robot serach engine or crawler, in this way you can obtain a high evaluation result and can lead to a high ranking position in a search engines.
The cost-effect of SEO are not always excellent than SEM cost-effectiveness, they differ according to the key words.
However, there is a necessity of using SEO measures when considering company branding by providing special key words.
The cost compare before, is from \100,000 a month.
Making use of both services is recommendable.
SEM result display SEM is a pay for click advertisement. Have a higher possibility of high ranking than search engines data base.