As expected, Facebook has launched a Subscribe button for websites, a social plugin any site owner can add to give visitors the option to subscribe to contributors in one click. For example, if ZDNet were to implement the button, you (the reader) would be able to subscribe to my (the journalist) public Facebook status updates. This is assuming two things happen: I have turned the feature on my Facebook account, and I have let ZDNet put such a button on my articles.
The Subscribe button for websites works just like the recently-added Subscribe button on Facebook; once clicked, the subscriber will begin seeing the public posts of the person they have subscribed to in his or her News Feed, alongside updates from their friends and the Pages they have Liked. Similar to the Like button, the Subscribe button can be easily added using XFBML or an iframe.
<fb:subscribe href="https://www.facebook.com/emil.protalinski" width="450"></fb:subscribe>
Here's the HTML5-compliant version for my profile:
Here's the iframe version for my profile:
frameborder="0" style="border:none; overflow:hidden; width:450px;"
Last but not least, here's my attempt to actually use the button:
If you're a Twitter user, here's the best way to explain this button to you: Subscribe is to Follow as Like is to Tweet. Twitter launched a Follow button in May 2011 (you can see mine below) and now Facebook is offering its equivalent.
Three months ago, Facebook announced Subscriptions, an optional feature that lets you control what types of stories you get from your friends and non-friends in your News Feed. Subscriptions are meant to help you keep up to date with people you're not friends with.
In other words, these are one-way friendships for subscribing to a public figure, celebrity, politician, journalist, or anyone else who wants to post public updates via their Facebook profile. It benefits both parties: the subscriber (could be you), who wants to use Facebook to receive a person's updates, as well as the public figure (also could be you), who wants to reach their audience on Facebook without having a separate Page.
This new button will let you subscribe to a person's content when you're not on Facebook, like a news website, blog, and so on. Given how big Facebook is, and how popular the Like button is already, the Subscribe button will likely be adopted very quickly across the Web. Everyone who implements it will also likely see their subscriber numbers skyrocket as people will be discovered not just on Facebook, but across the whole Web.