This study is dedicated to the search engine marketing (SEM). It aims for developing a business model of SEM firms and to provide explicit research of trustworthy practices of virtual marketing companies. Optimization is a general term that represents a variety of techniques and methods of the web pages promotion. The research addresses optimization as a business activity, and it explains its role in the on-line marketing. Additionally, it highlights issues of unethical techniques utilization by marketers which created relatively negative attitude to them on the Internet environment. SEM is the largest part of on-line marketing, and it is a prerogative of search engines portals. However, skilled users (marketers) are able to implement long-term marketing programs by utilizing optimization techniques to increase web site visibility to search engines and, therefore, to attract user’s attention to the customer pages. SEM firms are related to small knowledge-intensive businesses. On the basis of data analysis accomplished in this work their business model was constructed. This book can be used as a guide for SEM start-ups and as a template for analysis of Internet companies.