In this paper, we draw a panorama of research on the handwriting recognition, from the recognition of isolated letters to the recognition of handwritten sentences. Without going into detail on the most advanced approaches, we present the issues and principles related to recognition of handwriting by doing many references that allow the reader to deepen the discussed concepts. We review the main elements of a recognition system: preprocessing, segmentation, modeling, learning, recognition, integration of language model... The main approaches are presented by focusing more specifically on online handwriting recognition. On-line handwriting recognition is related to new devices based on touch screens or interactive pen display: Tablet PC, Smartphone or Interactive Whiteboards.