In May 2013, Twitter users favorited tweets 1.6 billion times, according to data analytics company Topsy. That's four times the amount of favorites from May 2012.
Favoriting is essentially Twitter's version of
It's a way of saying you like the content without commenting on it or resharing it.
If someone tweets something controversial that you agree with, but don't necessarily want to broadcast, favoriting is the best option.
Favoriting really took off after Twitter redesigned its website in app in December 2011 (see chart below). At the time, Twitter updated its website and apps to include "interactions" in its "@a" mentions section.
Before then, favoriting was pretty private, as people were not easily able to see who was favoriting their tweets.
