Originally envisioned as a method of organization, the hashtag has gone from an obscure idea to an indelible part of our communication landscape.
They were used to clap back at a racist cartoon and express grief for the Syrian war. The world in 2016, captured in hashtags.
A trending hashtag on Twitter invites people to personify countries in Africa with various schoolyard archetypes.
Nigerian netizens are using the hashtag #CaptainAmericaInNigeria as a vehicle for cheeky social and political commentary.
If it didn't hashtag, did it really happen? We look back on the trendiest hashtags in global development in 2015.
Do a quick search of #DayoftheGirl and you'll find dozens of related hashtag campaigns. Does that help further the cause or water down the message?