Advances in data science and machine learning have allowed for the analysis of increasingly complex and large data-sets. Digital devices are a source of such data, given their ability to collect information on users continuously and irrespective of location. Digital phenotyping aims to use these data to build a comprehensive picture of an individual's behaviour. Psychiatry is well-positioned to make use of this, since digital behaviour may be reflective of mental state. This article provides an overview of the field of digital phenotyping as it stands currently, on the verge of large-scale studies which may pave the way for clinical implementation in psychiatry.