When it comes to social media, the one thing that small and midsize businesses want to know is this: Is it worth it?

Yes, it is. Here are five reasons why.

1. It helps you stay ahead of the competition

A recent study by the Center for Marketing Research at the University of Massachusetts Dartmouth found that America's fastest-growing private companies adopt social-media-marketing initiatives at much higher rates than other companies.

Vistaprint, a company specializing in small businesses, conducted another study—on small business marketing trends—and found that small businesses are likely to increase their use of online-marketing tactics in the coming year.

The takeaway: Small businesses that are embracing online tactics now will grow at a higher rate in the future. If they haven't already, your competitors will extend their marketing into social media in 2010, trends indicate. Those who adopt social media are poised for faster growth and increased sales. Are you?

2. It extends your reach

Facebook has 500 million followers, up 25% from less than a year ago.