In the era of the quantified, commodified "friendship," there are few slights so keenly felt as the unspoken, unacknowledged unfriend. Now, for better or worse, you can revel in your own rejection: Who Deleted Me, a recently relaunched app for iOS, Android and Google Chrome, tallies in real time all the one-time friends fleeing your Facebook feed.

Read more:
• Modern etiquette: How do I decline Facebook friend requests?
• The most annoying Facebook status updates

Using the app is pretty simple, emotional consequences aside: After you download the app or browser extension, log in to Facebook through it and click "show me who" to see the people who have unfriended you, or left Facebook, since you last logged in. (The app doesn't work retroactively: You can only see your unfriends since you downloaded it.)

Similar tools are also available for Twitter, Tumblr and Instagram: Try Stalkr, Who Unfollowed Me and Unfollowers.com if you really want to feel bad about yourself.

Seriously, though: What prompts a long-time friend or acquaintance to suddenly lose interest in your updates, as 63 per cent of all social networkers say they have, at one point, done?

In a 2014 study, Christopher Sibona, a researcher at the University of Colorado at Denver, actually pinpointed the four types of content that are most likely to prompt an unfriend:

• Frequent/unimportant posts
• Polarising posts (politics and religion; liberals are, for what it's worth, more likely to unfriend over political views)
• Inappropriate posts (sexist, racist remarks)
• Everyday life posts (child, spouse, eating habits, etc.)

That same study found that we're most likely to unfriend people we know from work, high school or other, mutual friends: In other words, people we don't actually know that well, and people for whom we'd act a certain, specific way for IRL.

Sociologists have coined the term "context collapse" to describe the jarring experience of seeing an acquaintance's entire life laid out online, when you generally only see a specific, performed piece. (It can be jarring - even unfriend-worthy! - to say the very least.)

So before you take your unfriend-number to heart, consider Sibona's conclusions: "The general term of 'friend' on social networking sites can be misleading," he says, because most of the people we connect with on Facebook are not, and were never, actually our friends.

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