Social networking giant Facebook decided to step up into the overcrowded coupons market by offering users in five U.S. cities coupons for everything from wine tastings to concert tickets.

Now users can purchase the special Deals coupons directly from Facebook and get discounted prices or access to limited-availability goods. Facebook will take a cut of each transaction.

"Although the market has seen huge growth and there are big players already there, it's not something that's locked down," said Ray Valdes, an Internet analyst at research firm Gartner.

"I expect to see churn among the vendors as they try one thing and it works for a while and other vendors find new ways of better meeting users' needs," he said.

The coupons available on Facebook are specifically aimed at group activities, such as a river rafting trip, rather than for individual items such as a discounted pair of jeans. Facebook users can easily recommend interesting-looking deals to their friends on the service.

"It's not about taking someone else's business model and force-fitting it into Facebook," Emily White, director of local products at Facebook, told Reuters in an interview on Tuesday.

"Ultimately we're providing what we hope is a really great user experience by looking at what people come to Facebook to do, and that's interact with friends," she said.