Laughter may be a universal language, but expressing it on social media is anything but as a new Facebook study reveals.

According to the social network's data, 15 per cent of posts to the social network featured "e-laughter." And while "lol" -- i.e. laugh/laughing out loud -- may have now entered the popular lexicon beyond the Internet's borders, Facebook's findings, based on studying anonymized posts from U.S. users across a single week in May, shows that it is in fact the least popular way of expressing amusement, on the world's largest social media site at least.

Only 1.9 per cent of those expressing laughter on Facebook use "lol" in order to do so, compared with 13.1 per cent who use a variation of "hehe" and 33.7 per cent who express their humor via an emoji. But, with a 51.4 per cent share, "haha" or variations of it is by far the most popular way of laughing online.

As for whether one way of expressing laughter is more popular than another among the sexes, Facebook found that female users are more likely than male users to post an emoji or to use "lol." Male users in turn were more likely to use "haha" or "hehe" but the differences are small. As for age, whether a user was 13 or 70 or any age in-between, "haha" was always the most popular form of expressing humor on Facebook.

However, when Facebook researchers drilled down further, they found that the median age of emoji users is the youngest while the median "lol" user is the oldest, although in all cases that median age is younger than 30.

Other notable findings from the study, which was conducted in response to an article in the New Yorker about online laughter (and which Facebook points out was based on anecdotal evidence, rather than data), include that of those users who do laugh online, 46 per cent laughed just once in a week and 85 per cent posted fewer than five laughs in a week.

Facebook also decided to see if types of laughter were more popular in different U.S. cities, comparing behavior in Boston, Chicago, New York, Phoenix, San Francisco and Seattle. People in Chicago are the most likely to use an emoji and those in Seattle the least likely. The use of lol spikes in Phoenix and dips the greatest in New York, while those in San Francisco are the most likely to use "hehe" and in Seattle, "haha" tops the charts.