Social network users in Europe will reach 107.4 million in 2012, up from 41.7 million in 2007, according to Datamonitor.

The UK is expected to be the biggest grower in social networking over the next five years, up from 9.6 million users in 2007 to 27.1 million in 2012.

That growth will be driven by the increasing time spent online, as well as the convenience of socialising from home and the freedom of expression provided on social networks, eMarketer reported.

According to Matthew Taylor, analyst at Datamonitor, in a press release, "The wealth of information stored on online social networks provides many potential benefits for marketers."

"This potential has been recognised for a while, but many companies remain unsure regarding the best way to approach this relatively new media. As a result, the success of campaigns through social media has so far been mixed," Taylor added.