Airbnb got 30% more engagement by changing from an icon from a star to a heart

"For a couple years, registered Airbnb users have been able to star the properties they browse, and save them to a list. But Gebbia’s team wondered whether just a few tweaks here and there could change engagement, so they changed that star to a heart. To their surprise, engagement went up by a whopping 30%. The star, they realized, was a generic web shorthand and a utilitarian symbol that didn’t carry much weight. The heart, by contrast, was aspirational. "It showed us the potential for something bigger," Gebbia tells Co.Design. And in particular, it made them think about the subtle limitations of having a search-based service. "You have to have search," Gebbia says. "But what if you don’t know where you want to go?""
Source:  Fast Code Design, October 2012