David Hallerman, eMarketer senior analyst, calls search a brief way station that users jump from, moving from a search engine to one Web site and, perhaps, to another. During each movement from page to page, users' actions are tracked and recorded through the browser. Google and Yahoo monitor that browser behavior. And although the two engines separately provide a way to opt out of ad targeting, a recent post by Zachary Rodgers at ClickZ suggests that not many people choose, or take the time, to do so. In fact, a rough calculation suggests about 6,600 of Google's users, at the most, opt out of ad targeting per week, Rodgers writes. It appears that behavioral targeting will become an accepted practice. People will want to see ads that can provide them with the knowledge to make informed decisions. They just will need to keep in mind that brands speak to them in marketing tongue, so they shouldn't take the message at face value. The question becomes whether the engines will consider using real-time tweets and status updates from MySpace and Facebook as a targeting method to reach people searching for information, products or services on the Web. And whether using that data to target behavior is, indeed, a breach of privacy. Hallerman notes that it's one thing for search engines to take the keyword data you searched for and use it to determine advertising metrics, and yet another to tap into the semi-personal tweets from Twitter or social network posts from Facebook to target or retarget ads toward people based on behavior and searches. Well, it appears more people have become aware of ad targeting during the past five years, but not many people seem to want to take action to stop from being targeted -- not even with paid search ads. Paid search ads are a form of behavioral targeting. The search-based ads serve up not only in engine queries on Google, but most Web mail systems, such as Gmail. Such systems interpret words used in a keyword query or in a social network site to target users with ads. "Most paid search ads are not news-based or what's hot, but rather product-based," Hallerman says. "If the name of a product turns up in a paid search ad, then, of course, the ad could target the Twitter feed." Companies will continue to tap into behavioral targeting. For example, in a recent interview, Neil Ashe, CBS Interactive's president, said the company's new ad strategy will include not only a move away from ad networks, but a move toward more ad-targeted programs, adding internal behavioral targeting programs in the first quarter.