Physics Prospects --Why Do We Want a Linear Collider?--
  The need to understand physics of electroweak symmetry breaking is reviewed. An electron positron linear collider will play crucial roles in that respect. It is discussed how the LHC and a linear collider need each other to understand symmetry breaking mechanism unambiguously. Two popular scenarios, supersymmetry and technicolor-like models, are used to demonstrate this point. 
Hitoshi Murayama (UC Berkeley, LBNL)