An enigmatic sign, the figure/form ‘X’ conjures meaning as a symbol, signfier, number and text. Traversing cultures, beliefs, and knowledge systems, an X can prohibit and denounce, approve and correct, combine and connect. As a figure, X evokes human presence, from a mark found in prehistoric caves to the symbol for a female chromosome which is universal to women and men. It also encapsulates mystery and allure, being an unknown variable, an axis on a map, sign of hidden treasure, and a signifier of special qualities – the ‘X-factor’.