Two out of three small businesses now have an online presence, a big leap from just a year ago. It’s no wonder the advertising agencies and search engine optimization (SEO) companies that are helping to guide their entry into the digital world are growing fast. The Valley is home to two large public online advertising companies, ValueClick Inc. and ReachLocal Inc., and now also a host of smaller firms vying for the business of area dentists, lawyers, insurance agents and beauty salons, all of whom need an online strategy. Of the 60 fastest growing private companies on our List, five are in the internet advertising or search engine optimization business. Their goal: to help take local companies out of the yellow pages and onto the worldwide Web. Moorpark executive Bruce Clay of Bruce Clay Inc. wrote the book on search engine optimization: literally. Search Engine Optimization for Dummies is sold at major bookstores and online sites such as Amazon, but the business of SEO is not for dummies, nor do-it-yourself hobbyists. With more and more companies online, standing out or rising to the top of a search engine’s rankings is becoming increasingly difficult. It’s why 44 percent of business owners attempted to carry out their own search engine optimization last year, down from 51 percent the year before, according to the 2011 State of Search Marketing Report produced by the Search Engine Marketing Professional Organization (SEMPO), the professional association of search engine marketers. It’s also why the SEO and the online advertising business remain white hot despite the recession. Nine out of 10 companies used SEO, and in 2011, they were on pace to buy services worth $19.3 billion, according to SEMPO. That’s a 16 percent increase from 2010. Among the new services in demand: guidance with social networks, mobile applications and rich content, like producing videos. According to the research firm Gartner Inc., by 2015 companies will be generating 50 percent of their Web sales from social networks and mobile apps, so figuring this stuff out is critical for small and large businesses alike. All this has been good news for Valley companies such as National Positions of Agoura Hills and Bruce Clay. National Positions grew 165.9 percent over a three-year period. Sales reached $10.9 million in 2010. Bruce Clay, an industry veteran who some say coined the word SEO, rang up $4.5 million in revenue and recorded a 66.7 percent gain over three years. Seed Corn Advertising, which is primarily a pay-per-click advertising company, grew 55 percent over three years and produced $5.1 million in revenue and Ebridge Inc. grew 31.9 percent to $32.4 million. And you can read about Scorpion Design, which grew 143.3 percent over three years to $8.2 million, on page 17. All of the companies were started by entrepreneurs who for one reason or another wanted to bust out of the corporate world and run their own business. While these entrepreneurs enjoy the freedom that comes from running their own business, they are first to admit the business is getting more competitive all the time. Between the two public companies in the business here in the Valley — ValueClick and ReachLocal — and the competition among themselves, they always have to remain a step ahead. Read how these entrepreneurs started out and are staying ahead in the profiles that follow.