This time last year Facebook membership was reserved exclusively for students, and it was the 138th most visited website in the UK. Then in September it opened itself up so that anyone could join, and its membership started to grow exponentially.

Facebook, which attracts an older and more affluent audience than the other big social networks, is now the 10th most visited website in the UK. In fact, 3 of the top 10 most visited websites in the UK in July were social networks, with Bebo at number 6 and MySpace at number 8.

Advertisers are well aware of the risks when working with websites that contain so much user-generated content. Recently, Vodafone, Virgin Media, The AA and other brands were reminded of these risks when they withdrew from Facebook after their adverts appeared alongside a British National Party profile.

Facebook is about keeping in touch with friends and meeting new people by creating and joining groups based around common interests. The largest of these are currently university or location-based (the 'London' network, for example, has 890,000 members), but many new and interesting networks spring up every day. Vodafone et al were concerned about being associated with the wrong type of group, and Facebook has responded by allowing advertisers to opt out of certain groups.

Unlike MySpace, companies cannot have their own page on Facebook, but communities can be, and often are, created around brands. A good example is 'Addicted to River Island', a Facebook group with over 600 members dedicated to the apparel retailer. This represents a group of loyal customers sharing their thoughts on new products and sale bargains, but what is the impact on the brand?

One good way to understand this is to measure the amount of traffic that Facebook sends to the River Island website. As a benchmark, Facebook ranks 20th in terms of delivering traffic to retail websites for the week ending 18 August. 4% of people leaving Facebook go to a retailer, and this number has doubled during 2007. In contrast, Facebook is the 10th most popular website visited before the River Island website for the week ending 18 August , and the amount of traffic it sends has increased 5-fold during 2007.

Facebook is also catching up with the more established Bebo and MySpace, not just in terms of visitors but also in traffic sent to retailers. Retailers in the Auctions, Department Stores, Books, Apparel & Accessories, and Music industries in particular should be on the look out for advertising opportunities and ways to take advantage of groups such as 'Addicted to River Island'.

Source: Hitwise UK