Conversion rate defines the ratio between the overall numbers of visitors to a certain website compared to the number of website visitors that perform an action desired by the website operator.
For example, visitors who take an action such as filling out a registration form or a questionnaire, subscribing to a newsletter or a blog, submitting details or comments, purchasing a product or ordering a service. Website administrative pages count everyone who views a page, and counts again each visitor who participates to determine the conversion rate score.
The higher that conversion ratio is, the higher search engines score the website. Higher conversion rates entitle the website owner to certain privileges like higher ranking on search engine pages, which translates to more visibility, more traffic and higher profits.