Pinterest has raised $225 million in a Series E funding round that values the image-focused social network at $3.8 billion. The social network has raised $564 million to date.

New investor Fidelity led the round, which also included existing investors Andreessen Horowitz, Bessemer Venture Partners, FirstMark Capital and Valiant Capital Partners.
Pinterest says it will use the capital to move into 10 additional international markets by year’s end.. Earlier this year it launched in the United Kingdom, France and Italy.

It also plans to invest in mobile, which accounts for roughly 75% of its traffic, as well as to continue to find ways to profit from its platform. Pinterest earlier this month took its first major step toward generating revenue by launching an initial test of ad units on the social network.

“We hope to be a service that everyone uses to inspire their future, whether that’s dinner tomorrow night, a vacation next summer, or a dream house someday,” says Ben Silbermann, Pinterest co-founder and CEO.

Pinterest is the 13^th most-visited site in the United States, according to Alexa Internet Inc., a subsidiary of Amazon.com Inc., and its average visitor spends more than 7 minutes and 36 seconds on the site per visit. Throughout the last few months the social network has been increasingly focused on shopping-related initiatives, a strategy that could help make Pinterest more attractive for retailer advertisers. For instance, in July it began rolling out price alerts, in which it automatically e-mails shoppers when a retailer drops the price of an item that she has “pinned.”

Pinterest is the social network where consumers can “pin” images and pictures of products they like from around the web. They often accompany those pins with a brief description or caption that appears below the image. Consumers add their pins to boards, which are organizational tools used to group pins together around a particular theme—for example, “Wedding inspiration.”

Those online scrapbooks prompt many Pinterest users to click from the site to retail sites. Pinterest accounted for 24.96% of retailers’ site traffic from social networks in the first quarter, according to an analysis by Monetate Inc. of its retail clients. And the average order value for shoppers who click from Pinterest is $80.54, which outpaced every other social network Monetate studied. That may help explain by 78% of the retailers in the 2013 Top 500 Guide are active on Pinterest.