In a recent study published by Internet Retailer, 55% of shoppers who signed into retail websites used Facebook - up from 41% last year. This is part of a growing trend for people to use one social profile as their persona online and their preference to be able to have what is essentially a single sign on to manage the many different sites where they have accounts. The study also found that while the majority of retail site visitors did use Facebook, Twitter, Yahoo, AOL and other profiles were also used to access those sites.
So what does that mean for you? With 65% of online adults and 80% of teens on at least one social network (according to Pew Internet research), providing those users with the option to sign on with their preferred profile could help you to not only increase engagement, but also provide you with bonafide data instead of junk emails or guest logins. Ultimately, it's about giving your visitors more options when they visit your site, so that they will be able to use your site however they feel most comfortable.
Before you limit your site to ONLY a Facebook login, though, be sure that most of your visitors are using Facebook and would prefer to log in to your site in that manner. If you have a very limited presence on Facebook with only a few followers, it's probably not the best idea to restrict all log-ins to Facebook. In fact, you could do more harm than good. When you provide options, you're ensuring your visitors have the best experience possible.