In this paper we present a new approach to visual servoing using lines. It is based on a theoretical and geometrical study of the main line representations which allows us to define a new representation, the so-called binormalized Pl ̈cker coordinates. They are particularly u well suited for visual servoing. Indeed, they allow the definition of an image line alignment concept. Moreover, the control law which realizes such an alignment has several properties: partial decoupling between rotation and translation, analytical inversion of the motion equations and global asymptotic stability conditions. This control law was validated both in simulation and experimentally in the specific case of an orthogonal trihedron.