ROI is Return On Investment, and it’s used to reference practices by which organizations quantify spending on outreach programs, usually of the marketing variety.
When it comes to web traffic, what is sought is an increase. The more web traffic a site can boast, the more profitable it becomes–generally.
Whether you are new to SEO or you are a seasoned marketer, there are exceptions to any rule; just consider the Obamacare website. For five billion dollars, the US government handed its citizens an irredeemable lemon, all ROI being negative for customers and provider.