(CBS) — For decades, companies have relied on TV, radio, magazines and billboards to advertise their products, but now many are turning to social media.

And those companies are finding word of mouth is giving them a growing voice for their products online.

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Blogging can be big business these days, and that’s apparent at the 9th Annual BlogHer convention at McCormick Place, billed as the web’s leading guide to the hottest news and trends among women in social media.

“If you’re a blogger, you don’t just blog anymore. You’re also a Tweeter, a pinner, a Facebooker, an Instagramer,” says Jory Des Jardins, co-founder of BlogHer.

Companies including Coca-Cola and SC Johnson want to cash in.

“It’s extremely important. We recognize that bloggers in the last few years have completely exploded,” Michelle Johnson of SC Johnson says. “Bloggers are a conduit and a means to talk to our consumers.”

Three hundred companies are showering more than 4,000 bloggers with attention and free samples, hoping it will lead to a positive blog or tweet about their product.

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“Purely profit,” blogger Mike Adamick says of corporate motives. “I mean, it’s a huge network.”

Companies say one of the best ways to get people to buy your product is to have them try your product.

Bloggers say it certainly works.

“I’ve seen how quickly it catches on and spreads the word, and I think people are always looking for just a trusted resource,” Aimee Eichelberger says.

In addition to the freebies, bloggers also get to share tips and ideas on how to improve their blogs.

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The BlogHer convention continues Saturday.