First used as puntuation, it's now a symbol that is related to depression and/or anxiety. It's used as a symbol that conects two sentences together, preventing the sentence from ending. It's also used as a metaphor, comparing it to life, or suicide, telling the victim of mental illness not to let their sentence end, or to not commit suicide and to keep going. People get a semi-colon as a tattoo to support the fight against mental illnesses.