Depending on your feelings about Google (and how much of its stock you own), the search giant's reported decline in pay-per-click advertising may leave you scared, smug or just uncertain.

More than any particular strengths or weaknesses about Google, the drop illustrates how tricky Internet advertising can be. Compared to other marketing mediums, the Internet is growing strongly, according to a Knowledge@Wharton article. Yet it still accounts for only a sliver of the overall advertising pie.

While the Internet offers companies more insight into customer behavior than other advertising channels, companies largely don't seem to know what to do with this knowledge, say experts.

And how much can companies trust this information, anyway, when many folks choose to adopt multiple online personas? Doing so is a defining trait of the so-called Generation V (for virtual), according to this interesting Baseline piece. Says the Gartner analyst credited with coining the term:

Having different personas online is no different than real life. People act differently when they go to the doctor than they do at a football game or at a parent-teacher conference," says Sarner. "We now need to recognize that people have a different set of desires on Amazon.com or while using Flickr or Second Life.

Such customers want online "experiences"rather than traditional marketing pitches. At least some business types will no doubt find it difficult to follow Gartner's advice, which includes:

• Organize and target online products and services based on a customer's journey toward self-actualization.

• Focus on the influencers within the meritocracy of virtual environments.

• Utilize automated, self-learning business intelligence applications called "persona bots" as a tool of mutual exploration.

"Mutual exploration" notwithstanding, companies must be careful not to get too cozy with their customers online, cautions the chief marketing officer of Internet brokerage Scottrade in the Knowledge@Wharton article. He says:

Never overwhelm the customer with a feeling that you know too much.

Companies must also familiarize themselves with a complicated online mix that includes search engines, social networking sites and affiliate networks. According to a recent JupiterResearch study, 87 percent of consumers visit multiple sites before making an online purchase, reports internetnews.com.

And let's not forget good, old bricks-and-mortar. Thirty-six percent of consumers browse and conduct research online -- but prefer to buy offline. The trick to appealing to these folks is blurring the line between virtual and real-world shopping environments.