Search engine marketing is the practice of marketing or advertising your web site through search engines, like Google, Yahoo or MSN. Search engine marketing (SEM) may consist of one or more of the following components: Organic Search Engine Optimization (SEO), Pay Per Click Advertising (PPC), Pay For Inclusion (PFI). Why is Search Engine Marketing Important? In today’s business climate, nearly all businesses are expected to have a website and most do. How do Chicago Online Advertising companies measure SEM Effectiveness? They measure the effectiveness of your search engine marketing program depends on what your objectives were when you started. If your intent was merely to increase the number of visitors to your web site, you would compare your web traffic statistics before and after you implemented search engine marketing.