Either if you are a manager in a large company or in a SMB and you need authorization to invest money you’re gonna need to explain carefully to your boss (or the owner of the company) «What is SEO» and «What are they going to do with our money?».
A pharagraph of a well known book from four aknowkledged experts in SEO: The art of SEO, can help you:

Chapter 3. Determining Your SEO Objectives and Defining Your Site’s Audience

art-of-seoSEO, once a highly specialized task relegated to the back rooms of a website development team, is now a mainstream marketing activity. This dramatic rise can be attributed to three emerging trends:

  • Search engines drive dramatic quantities of focused traffic, comprising people intent on accomplishing their research and purchasing goals. Businesses can earn significant revenues by leveraging the quality and relevance of this traffic for direct sales, customer acquisition, and branding/awareness campaigns.
  • Visibility in search engines creates an implied endorsement effect, where searchers associate quality, relevance, and trustworthiness with sites that rank highly for their queries.
  • Dramatic growth in the interaction between offline and online marketing necessitates investment by organizations of all kinds in a successful search strategy. Consumers are increasingly turning to the Web before making purchases in verticals such as real estate, autos, furniture, and technology. Organizations cannot afford to ignore their customers’ needs as expressed through searches conducted on the major search engines.

Search engine optimization, while a very technical practice, is a marketing function—and it needs to be treated like one. SEO practitioners need to understand the company’s services, products, overall business strategy, competitive landscape, branding, future site development goals, and related business components just as much as members of other marketing divisions, wether online or offline.