For many online marketing divisions, the click-through rate (CTR) may be the most important measure of success. Getting that search result in front of people is just the first step. Once you get your link onto the first page of the search results -- after all, most users never even get to the second page, much less results that are even further down -- you still need to get people to actually click that link and visit your site. Then the game shifts to trying to increase dwell times and keep them on the site, giving you a chance to make a sale. Your conversion rate is calculated by looking at what percentage of visitors make a purchase.