The forthcoming edition of Visualizar'18 (21 September-5 October) has chosen Personal Data as its theme. This theme is by no means unrelated to previous editions of Visualizar, as back in 2015 we dealt with data commons and in 2017, because of the migration - of data -, the result of the Tráckula project was an addon for Firefox that displays the entities that track our activity on the web when we visit almost every page - including this one.