Americans rank Facebook as the most important app on their smartphones, according to recent research from comScore.
The report was based on data from a survey of 1,033 smartphone users in the United States.
Some 37% of respondents select Facebook as one of the three mobile apps they cannot go without.
Gmail is next (34% of respondents say they cannot go without it), followed by Amazon (30%), Google Maps (24%), and Google Search (22%).