There are a lot of reasons to favorite a tweet: it's a way to bookmark it for later, or to show support to its poster, or, if you use a service like Stellar, to actually send it somewhere else. Favoriting is a rich culture unto itself, and one that is apparently changing.
In December of 2011, Twitter restructured its site (and later, apps) around four streams: Home, Connect, Discover and Me. Home and Me were minor updates to the familiar tweet list and profile, respectively, but Connect and Discover were different — particularly when it came to favorites. December was when they became truly visible for the first time.
Connect added "Interactions," which shows you clearly, in a list, who's been faving your tweets.
The Discover tab also added a new feature that shows your friends' favs.
(If you tap the Discover button in a Twitter mobile app, you'll see the them right away).
Favs became more prominent, in other words, and it felt like people were using them more. And they were — but in a strangely specific way. Twitter tells BuzzFeed that it saw a steep rise in favs of tweets that were meant for nobody but the poster (see the graph above — New Twitter = "Let's Fly"). Fist-bump favs. Favs like this:
This change in behavior might make favs less useful to Twitter, in a way — they're one of just a few actions the site can harvest to build a Facebook-style social graph. But it indicates a shift in what people think tweets are: objects rather than posts; units of media rather than simple links.
This kind of faving is also unmistakably similar to liking on Instagram, where, as on Twitter, the likes are public, but intended primarily for the poster.
And maybe — MAYBE — it's a sign that Twitter is getting a little bit friendlier.