The hashtag. First developed on Twitter back in 2007, and since then the idea has spread to every corner of the social media world. The intention of the hashtag was to make it much easier for users to search for content specifically. It is essentially a way to categorise information, without having to scour the entire website that you’re using. Facebook, Tumblr, Pinterest, Instagram and Google+ have all jumped on the twitter trend, although they may not all of been as successful as each other when it comes to this phenomenon.