If you've run ads on Facebook, you may have noticed that they show you a column for "Social %" in the dashboard for your ad performance. Here's what that means.
Social ads are only relevant to content on Facebook, not ads for your separate website. However, any good Facebook marketing strategy will incorporate at least a Fan page to complement your off-Facebook website or brick-and mortar store.
When setting up a CPC or CPM ad on Facebook, you have the option to target "Friends of people who are connected to" some Facebook page, group, or application that you operate. If you use this targeting option, you should see a 100% social rate for that ad on the dashboard because the ad will ONLY be shown to friends of your existing fans. Even if you do not select this option however, Facebook will still use its own algorithms to occasionally target your ads to people who fit your targeting criteria AND ALSO whose friends are already connected to your content.
So say you want to promote your local clothing store. You should have a fan page set up on Facebook to build a following of loyal customers. You will see the best results by promoting the fan page through CPC ads on Facebook and then using status updates, link posts, etc. to the fan page in order to bring users back to your website or into your brick-and-mortar store. You may want to target your Facebook ads to users within a certain radius of your city, as well as by gender, age, etc. depending on the type of products you sell.
Facebook will AUTOMATICALLY serve a social version of your ad to users it thinks are most likely to respond to it once in a while even if you don't explicitly select this option. Clicks on social ads do cost more - as much as 3x more - so this will raise your average CPC overall, but they also command a much higher click-thru rate, so you usually come out ahead. That means if I am a fan of your clothing store, any of my friends who also fit your criteria will see the social ad instead of the regular one.
What makes an ad social?
The link, image, and text are the same as the ad you created. However, Facebook adds a message such as "Vince Arovola likes this" below it, hinting that my friend viewing the ad should also like it since I do. What's more, they also put the "Like" link right there next to it so my friends can become fans of the page without even actually clicking through to the ad. Facebook still counts this as a click, and also an "action" on your dashboard.
So... you might see on your dashboard that your ad got 100,000 impressions, 100 clicks, 50 actions, and 10% social. That means 100 people (0.10%) either clicked the ad itself OR directly on the Like link, 50 people (or half of the clicks) became new fans and now subscribe to your page's status updates, and 10% of the 100,000 total impressions were served as social ads to friends of your existing fans.