Project Semicolon was born from a social media movement in 2013.They describe themselves as a "movement dedicated to presenting hope and love to those who are struggling with depression, suicide, addiction, and self-injury. Project Semicolon exists to encourage, love, and inspire."
But why a semicolon?
"A semicolon is used when an author could've chosen to end their sentence, but chose not to. The author is you and the sentence is your life." Originally created as a day where people were encouraged to draw a semicolon on their bodies and photograph it, it quickly grew into something greater and more permanent. Today, people all over the world are tattooing the mark as a reminder of their struggle, victory, and survival. 
Source:  www.upworthy.com​