In a keynote speech delivered yesterday afternoon at Marketing Week’s Digital Day, the head of Google Canada identified five key areas of understanding his company believes are critical to marketers’ success on the web.

Prior to explaining these five points, Jonathan Lister, who also serves as Google’s marketing director, argued that the Internet has now entered its third distinct stage of development in terms of its use by marketers.

In the early days of the web, said Lister, companies used the medium primarily as a home for digital versions of flyers and brochures. He credited companies such as Amazon and eBay for ushering in a second phase in which e-commerce developed.

Lister said the current “3.0” phase is based on the desire of both consumers and marketers to form communities, express themselves and create entertainment online, using tools such as Facebook and YouTube.

According to Lister, the proliferation of social media and online video is creating radical social and commercial changes.

“Two-thirds of the world’s Internet population visits social networking sites, which account for about 10% of all internet traffic,” said Lister. “In the next five years, about a quarter of entertainment on the web will be user-generated,” he added.

Lister said these statistics pointed to the first of his five key points–that the online world is changing so rapidly that marketers cannot simply assume that what worked previously will be effective going forward.

“The way you bought search and the way you bought marketing in general years ago, it has to be different now,” he said.

Lister also urged marketers to acknowledge the way that online and offline media can complement each other in an age when consumers move frequently and effortlessly between both. Underscoring a point made by his Google colleague Bill Tighe in a presentation earlier in the day, Lister noted that, for example, more than two-thirds of online searches for specific brands, products and services are spurred by offline advertising.

Lister’s third major point was that, in an online environment that includes more than 600 million registered domain names, advertisers must continually find new ways to battle the sheer volume of content and information. Part of this equation, he said, was an effective search strategy that ensures a marketer gets the highest possible ranking when consumers search relevant terms.

Saying that 71% of consumers associate top search placement with reliable and successful brands, Lister encouraged the audience to “understand consumer perception and advertise accordingly.”

Lister also challenged the conventional wisdom that determining the value of marketing is next to impossible. Marketing, he said, will someday be an easily measurable discipline, with online leading the way due to the quality of data produced by companies like Google.

“We’re entering a new era in marketing,” he said. “We’ve moved to a stage where data beats opinion.”

Lister wrapped up his presentation by counseling marketers not to be afraid to bet on an emerging trend. He identified mobile technology and online video as emerging areas where marketers can and should stake out space.

“The time is now to get ahead of these trends,” said Lister. “Especially mobile, which isn’t yet overdeveloped.”