In this chapter we define parametric interval linear systems and characterize various types of parametric solution sets. We provided as well several visualizations of the most general (united) solution set (in 2D and 3D) that aim to facilitate the exploration of the properties of this solution set. We start with a brief introduction to interval linear systems (Neumaier, Interval methods for systems of equations. Cambridge University Press, Cambridge, 1990) , (Rohn, Interval linear systems. Freiburger Intervall-Ber. 84/7. Universität Freiburg, Freiburg, 1984)  from which parametric interval linear systems originate.